Thèses sur le sujet « Metaboliti volatili »
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1
Andreola, Diego <1991>. « Elaborazione di un metodo di analisi per la determinazione di metaboliti volatili che consentono l'individuazione in fase precoce della presenza di muffe in ambienti chiusi mediante GC-MS e desorbimento termico ». Master's Degree Thesis, Università Ca' Foscari Venezia, 2018. http://hdl.handle.net/10579/12137.
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La presente tesi conduce alla realizzazione di un metodo analitico efficace prendendo lo spunto iniziale nel lavoro di ricerca svolto da Stephane Moularat, brevettato nel 2012, che ha messo a punto uno schema algoritmico a risposta binaria considerando 16 diversi metaboliti prodotti dalle muffe ed altri 4 composti di natura sesquiterpenica. La risposta positiva o negativa, dovuta alla presenza o meno dei composti indagati nell’aria dell’ambiente campionato, porta ad un risultato definito come Indice di Contaminazione Fungina (ICF). Tale risultato viene dunque tradotto nella presenza (ICF > 0) o assenza (ICF < 0) di muffa nell’ambiente sottoposto all’analisi.
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Hess, Joerg. « Modelling the transport of volatile metabolites in the mouth ». Thesis, University of the West of England, Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490457.
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The knowledge of the mechanisms giving rise to halitosis in the mouth is quite limited despite the social constraints the condition imposes and the attendant commercial interest that results. In part, this understanding is limited by the difficulties inherent in undertaking in vivo studies which are further exacerbated by the complexity of the systems under investigation, in particular, the influence of transport mechanisms such as salivary flow, pH, temperature and others had not been investigated. The research described here is based on a new approach to investigate the transport mechanisms contributing to oral malodour emanating from the tongu, dorsum as the main source of volatile compounds in the mouth (Yaegaki and Sanada 1992, Rosenberg and Leib 1995, De Boever and Loesche 1996).
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El-Kader, M. S. A. M. A. « Production of Volatile Secondry Metabolites in Plant Tissue Cultures ». Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503643.
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Turon, Violette. « Coupling dark fermentation with microalgal heterotrophy : influence of fermentation metabolites mixtures, light, temperature and fermentation bacteria on microalgae growth ». Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS201/document.
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La production de microalgues en hétérotrophie présente plusieurs avantages pour la production de biocarburants par rapport à la production autotrophe, comme une productivité plus importante en termes de biomasse et de lipides. Cependant, le développement industriel de ce procédé est limité par les coûts de productions associés au substrat organique (i.e. glucose) et à ceux liés à la stérilisation des fermenteurs. Les effluents de fermentation sombre, composés principalement d’acétate et de butyrate, pourraient être utilisés comme milieux de culture peu onéreux pour la culture hétérotrophe ou mixotrophe de microalgues. Les objectifs de cette thèse étaient i) de mieux appréhender la croissance algale sur des mélanges variés d’acétate et de butyrate en fonction de la présence ou l’absence de lumière et de la température de croissance et ii) d’évaluer la faisabilité d’utiliser des effluents de fermentation non stérilisés pour soutenir la croissance de microalgues oléagineuses. Tout d’abord, un modèle basé sur des bilans de masse a été construit afin de caractériser la croissance hétérotrophe de Chlorella sorokiniana et Auxenochlorella protothecoides (taux de croissance et rendements) sur des mélanges d’acétate et de butyrate. Les résultats ont montré que le rapport acétate:butyrate et la concentration en butyrate étaient deux paramètres clés pour soutenir la croissance hétérotrophe. Puis, il a été démontré que la présence de lumière et l’utilisation d’une température suboptimale (30 °C) pour la croissance algale permettaient de réduire l’inhibition du butyrate en permettant une production de biomasse autotrophe ou en améliorant la croissance sur acétate. Enfin, il a été montré que les microalgues peuvent être compétitives sur l’acétate lors de la croissance sur des effluents bruts de fermentation sombre en présence de bactéries fermentaires, grâce à la croissance rapide des microalgues sur acétate (1.75 j-1) et à un changement drastique des conditions de culture peu favorables à la croissance des bactéries d’origine fermentaireGrowing microalgae in heterotrophic mode present several advantages over autotrophic mode such as a higher productivity in terms of biomass and lipids for biofuels production. Nevertheless, this process is limited by the production cost associated with the organic substrate (i.e. glucose) and fermenters sterilization costs. Dark fermentation effluents, mainly composed of acetate and butyrate, could be used as a low-cost medium to grow microalgae heterotrophically or mixotrophically. The aims of this PhD were i) to optimize microalgae growth on various mixtures of fermentations metabolites using the presence or absence light and different cultivation temperatures and ii) to assess the feasibility of using unsterilized fermentation effluents. First, a model based on mass balance was built to characterize heterotrophic growth rates and yields when Chlorella sorokiniana and Auxenochlorella protothecoides were supplemented with different mixtures of acetate and butyrate. Results showed that the acetate:butyrate ratio and the butyrate concentration per se were two key parameters for promoting heterotrophic growth. Then, further studies showed that the presence of light and the use of suboptimal temperature (30 °C) could reduce the butyrate inhibition on growth by either triggering autotrophic production of biomass or enhancing growth on acetate. Finally, it was shown that microalgae could outcompete fermentation bacteria for acetate when growing on raw dark fermentation effluents, thanks to a fast algal growth on acetate (1.75 d-1) and a drastic change of culture conditions to the detrimental of bacterial growth
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Cheung, William Hon Kit. « Metabolic profiling of volatile organic compounds and enhanced vibrational spectroscopy ». Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/metabolic-profiling-of-volatile-organic-compounds-and-enhanced-vibrational-spectroscopy(adcff7c7-96e3-4b5a-8d77-4a943b75f211).html.
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Metabolomics is a post genomic field of research concerned with the study of low molecular weight compounds within a biological system permitting the investigation of the metabolite differences between natural and perturbed systems (such as cells, organs and tissues). Rapid identification and discrimination of biological samples based upon metabolic differences and physiological status in microbiology, mammalian systems (particularly for disease diagnosis), plants and food science is highly desirable. Volatile organic compound (VOC) profiling is a novel area of research where the composition of the VOCs emitted by the biological samples can be correlated to its origin and physiological status. The aim of this project was to investigate the applicability of VOC profiling as a potential complementary tool within metabolomics.In this project the discrimination of bacteria using a novel gas phase separation method was investigated and the development of VOC-based profiling tools for the collections of VOCs emitted from biological samples was also studied. The optimisation and validation of a high throughput method for VOC analysis was achieved and this was used to assess wound healing.VOC metabolite profiling was further extended to the discrimination of S. typhimurium contaminated meat; the study was conducted in parallel with metabolite profiling analysis for the analysis of non-volatile small molecules. Finally, enhanced vibrational spectroscopic techniques were applied to the characterisation and screening of dye molecules in contaminated foodstuffs using Raman spectroscopy. This thesis clearly demonstrates that VOC metabolic profiling is a complementary tool within the metabolomics toolbox, one of its great attractions is that it permits the characterisation of biological samples in a rapid and non-invasive manner. The technique provides detailed chemical information regarding the VOC composition present above the headspace of the sample and can be used to understand its physiological status and biological origin. VOCs metabolite profiling will become a valuable tool for non-invasive analysis of many biological systems. Raman spectroscopy is a sensitive and non-destructive technique which can generate detailed chemical and structural information regarding the analyte under investigation with little or no sample preparation needed. The effect of the weak Raman signal can be significantly amplified by coupling the analyte molecule to surfaces of nanoparticles and demonstrated that it is ideal for analysing aqueous dye solutions in a quantitative manner.
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Berrou, Kevin. « Développement d’outils innovants pour l'étude de l’infection chronique ». Thesis, Nîmes, 2019. http://www.theses.fr/2019NIME0001.
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Un des enjeux majeurs dans la gestion de la plaie de pied diabétique est l’obtention d’informations permettant d’anticiper l’évolution de ces infections. Actuellement, il n’existe pas d’outils suffisamment efficaces qui permettent de distinguer une plaie colonisée d’une plaie infectée. L’approche proposée est basée sur discrimination de plusieurs bactéries fréquemment retrouvées dans les plaies chroniques de pied diabétique à partir de leur profil métabolique, et plus particulièrement des métabolites volatils qu’elles produisent. En effet, le dynamisme du métabolisme bactérien serait à même de mettre en évidence les changements qui s’opèrent dans la plaie. Dans un premier temps, une nouvelle méthodologie de concentration des métabolites volatils par Stir Bar Sorptive Extraction (SBSE) a été développée. Elle est basée sur l’utilisation de barreaux qui sont placés à la fois dans le milieu de culture et en espace de tête, suivie d’une analyse par GC-MS. La méthode a ensuite été comparée avec une autre méthode de concentration utilisant des fibres (la SPME) et a montré une meilleure capacité de concentration, permettant ainsi une détection plus sensible. Cette méthodologie a ensuite été utilisée pour suivre la production métabolique de six souches bactériennes cultivées dans des conditions mimant la plaie chronique. Grâce à leur profil métabolique, il a été possible de distinguer des espèces bactériennes. De plus, de manière plus surprenante, il a été possible de distinguer deux souches de Staphylococcus aureus présentant des profils de virulence différents. Enfin, une étude en co-culture a mis en évidence que 83% des métabolites produit en culture simple étaient retrouvés, prouvant l’intérêt de la méthodologie pour distinguer des souches bactériennes d’une même espèce au sein d’une plaieOne of the major challenges in the management of diabetic foot wounds is to obtain information to anticipate the evolution of these infections. Currently, there are no sufficiently effective tools to distinguish a colonized wound to an infected wound. The proposed approach is based on the discrimination of several bacteria frequently found in chronic diabetic foot wounds from their metabolic profile, and more specifically the volatile metabolites they produce. Indeed, the dynamism of bacterial metabolism would be able to highlight the changes that are occurring in the wound. First, a new methodology for the concentration of volatile metabolites by Stir Bar Sorptive Extraction (SBSE) was developed. It is based on the use of stir bars that are placed both in the culture medium and in headspace, followed by GC-MS analysis. The method was then compared with another concentration method using the fibres (SPME) and we highlighted a better concentration capacity with a more sensitive detection. This methodology was then used to monitor the metabolic production of six bacterial strains grown under conditions mimicking the chronic wound. Their metabolic profile allowed us to distinguish bacterial species. Moreover, more surprisingly, it was possible to distinguish two strains of Staphylococcus aureus with different virulence profiles. Finally, a co-culture was performed and we showed that 83% of the metabolites produced in simple culture were found, proving the interest of the methodology to distinguish bacterial strains of the same species within a wound
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Sohrabi, Mohsen. « Oral Microbiota and their Volatile Metabolites in Oral Squamous Cell Carcinoma ». Thesis, Griffith University, 2016. http://hdl.handle.net/10072/366691.
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The majority of the oral neoplasms are oral squamous cell carcinoma (OSCC) which have been traditionally linked to consumption of tobacco and alcohol. The human papillomavirus (HPV) infection is also significantly associated with OSCC progression. However, the prevalence of this cancer in people with no record of those traditional factors emphasized the possibility of another significant factor that potentially contributes to OSCC. Bacteria have been strongly associated with some cancers especially in gastric cancer. Several microbial metabolites are categorised as carcinogens that suggest the direct and indirect role of microbes in cancer development. The new insight into human microbiome using high- throughput technologies revealed the variation in the human microbiota between healthy adults and cancer patients that have not been achieved using low- throughput methods. The oral microbiota analysis in OSCC using high- throughput technologies limited to the analysis of the bacteria associated with the cancerous site and the analysis of OSCC’s intraoral microbiota is understudied.
The human microbe-metabolite association with cancer was obtained previously, and the results indicated a potential use of human sample metabolites for the differentiation between healthy adults and cancer patients. However, the method employed in those studies was not ideal for the analysis of microbial metabolites independently from human metabolome. This is because that the accuracy and reproducibility of direct human sample metabolomics undergo variations with both human and microbial samples.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Medical Science
Griffith Health
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Moalemiyan, Mitra. « Volatile metabolic profiling to detect and discriminate diseases of mango fruit ». Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97971.
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Volatile metabolites from headspace gas of mango cultivars Tommy Atkins and Keitt, wounded and inoculated with two pathogens, Colletotrichum gloeosporioides and Lasiodiplodia theobromae or non-inoculated controls were profiled using a GC/MS to develop a technology to discriminate diseases. Several disease discriminatory compounds were identified and classified into three groups: (i) compounds unique to only one treatment; (ii) compounds common to two or more treatments but not to all; and (iii) compounds common to all treatments but with varying in their abundance. 1-pentanol and boronic acid ethyl were detected in only Lasiodiplodia-inoculated mangoes while thujol was observed only in Colletotrichum-inoculated mangoes. Models based on significant mass ions classified up to 100% of the diseases/inoculations. The disease discriminatory compounds and discriminant analysis models developed here could be used in the early detection of postharvest diseases of mango fruit, after validation under commercial conditions.
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Robert-Hazotte, Aline. « Impact du métabolisme des molécules odorantes sur la perception olfactive chez l'Homme ». Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCK073.
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L’odorat est le sens qui permet de percevoir des substances volatiles appelées communément odeurs. Il joue un rôle important dans la subsistance et le bien être des individus car il intervient dans la communication avec leur environnement (recherche de nourriture, de partenaire, détection des prédateurs ...). L’efficacité du système olfactif repose en grande partie sur sa sensibilité, qui dépend de l’affinité des molécules odorantes pour leurs récepteurs olfactifs mais aussi d’un mécanisme de clairance enzymatique des molécules odorantes qui évite à ces récepteurs d’être saturés et qui implique les Enzymes du Métabolisme des Odorants ou EMO. En effet, des études récentes ont démontré que dans l’épithélium olfactif, les EMO qui biotransforment les molécules odorantes conduisent à l’arrêt du signal olfactif en désactivant ces molécules, ce qui permet leur élimination et participent donc ainsi in fine à la perception olfactive. Dans ce contexte, l’objectif de ce travail de thèse est d’apporter une meilleure compréhension des mécanismes enzymatiques impliquant les EMO dans la perception olfactive des mammifères et d’étudier plus particulièrement ces mécanismes chez l’Homme.Le premier axe de ce travail, basé sur des analyses physico-chimiques, a consisté à développer une technique innovante de spectrométrie de masse par réaction de transfert de protons (PTR-MS) permettant le suivi en temps réel de la biotransformation des molécules odorantes par les EMO. Cette technique a été utilisée ex vivo sur des prélèvements d’épithélium olfactif et du mucus olfactif de rat et de lapin et également in vivo directement au sein de la cavité nasale humaine. Ainsi, il a été démontré que la biotransformation olfactive de molécules odorantes catalysée par différentes enzymes de type glutathion transférases, carboxylestérases ou dicarbonyl xylulose réductases (DCXR) est un mécanisme très rapide (de l’ordre de la milliseconde) en parfaite adéquation avec la dynamique physiologique du processus olfactif. Ces analyses ont également révélé que la biotransformation des molécules odorantes peut conduire à la production de métabolites volatils odorants pouvant potentiellement participer à la perception olfactive globale en interagissant eux aussi avec les récepteurs olfactifs. Ces différents métabolites ont été formellement identifiés par une technique de chromatographie en phase gazeuse couplée à la spectrométrie de masse (GC-MS).Le second axe de ce travail, reposant sur des analyses psychophysiques, a consisté à évaluer l’impact du métabolisme des molécules odorantes sur la perception olfactive chez l’Homme. Pour atteindre cet objectif, une stratégie originale de modulation de la perception olfactive reposant sur une compétition entre des molécules odorantes métabolisées par une même EMO, développée récemment au sein de l’équipe chez le lapin, a été transposée à l’Homme. La compétition entre des molécules odorantes de type dicétone vis-à-vis de l’enzyme DCXR a tout d’abord été démontrée in vitro par des analyses biochimiques sur l’enzyme recombinante humaine. Une méthode d’analyse par olfactométrie, appliquée à un panel de 40 sujets, a permis de démontrer que ce mécanisme de compétition entre molécules odorantes induit des modulations de la biotransformation de ces molécules conduisant ainsi à des modifications de leur biodisponibilité relative et in fine de leur perception. Ces résultats inédits démontrent que des modulations affectant la biotransformation d’un odorant conduisent instantanément à une modification de sa perception. Ces travaux de thèse précisent la fonction des EMO chez les mammifères et révèlent pour la première fois, chez l’Homme, une participation significative du métabolisme des molécules odorantes dans la perception olfactiveThe sense of smell permits the perception of volatile substances commonly known as odors. This sense plays an important role in the feeding and wellness of individuals because it involves exchanges with their environment (search for food or partners, predators detection…). The efficiency of the olfactory system mainly relies on its sensitivity depending on the odorant affinity for their olfactory receptors but also on an enzymatic clearance mechanism of odorants which involves the Odorant metabolizing Enzymes (OME) to avoid the saturation of the receptors. Recent studies have shown that the biotransformation of odorants by EMO, in the olfactory epithelium, participates in the olfactory perception. Indeed, OME catalyse the deactivation of the odorants and their subsequent elimination which led to the termination of the olfactory signal. In this context, this work aims to provide a better understanding of the enzymatic mechanisms of the OME in mammal olfactory perception and to study more specifically these mechanisms in human.The first axis of this work, based on physicochemical analysis, has consisted to develop an innovative proton transfer reaction mass spectrometry technique (PTR-MS) to allow the analysis in real time of the odorants biotransformation by OME. This technique was first applied ex vivo using rats and rabbits olfactory epithelium and olfactory mucus but also in vivo directly inside the human nasal cavity. Thus, we have demonstrated that the olfactory biotransformation of odorants catalyzed by different enzymes like glutathione transferases, carboxylesterases and dicarbonyl xylulose reductases (DCXR), is a very fast mechanism (few milliseconds). This very high velocity is perfectly consistent with the physiological dynamics of the olfactory process. Moreover, PTR-MS analyzes revealed that the odorants biotransformation could produce volatile metabolites with odorous properties which could participate in the global olfactory perception by interacting also with olfactory receptors. These various metabolites have been formally identified by a gas chromatography-mass spectrometry technique (GC-MS).The second axis, based on psychophysical method, evaluated the impact of the odorant metabolism in the human olfactory perception. For this purpose, an original approach recently developed in the lab, consisting of the modulation of the olfactory perception through a competition between odorants metabolized by the same EMO was transposed from the rabbit model to the human. The metabolic competition between several diketones toward DCXR was first demonstrated by biochemical analysis using the corresponding human recombinant enzyme. Then, an olfactometric study carried out on a 40 subjects panel demonstrated that this competition mechanism between odorants induces modulations of the biotransformation of these molecules and thus leads to modifications of their relative bioavailability and in fine of their perception. These new and significant results demonstrate that modulations impacting odorants metabolism leads immediately to changes in their olfactory perception. This thesis highlights on the function of EMO in mammals and reveals for the first time in human a significant role of the odorant metabolism in olfactory perception
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Bahroun, Najat. « Detection of Salmonella in food samples using exogenous volatile organic compound metabolites ». Thesis, Northumbria University, 2017. http://nrl.northumbria.ac.uk/32550/.
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Rapid, sensitive and selective detection and identification of pathogens is required in the prevention and recognition of problems related to food security. Salmonella is one of the dangerous foodborne pathogens. The identification of specific volatile organic compounds (VOCs) produced by Salmonella may contribute in providing a fast and accurate detection method for Salmonella in food samples. In this study, VOCs liberated by Salmonella strains have been identified and quantified via head space-solid phase microextraction coupled to gas chromatography/mass spectrometry (HS-SPME GC/MS). The dominant chemical class of volatiles liberated from Salmonella strains was alcohol compounds. In addition, ester and ketone compounds were also detected. The most sensitive VOCs detected were ethyl octanoate (LOD = 62.0 ng/mL and LOQ = 207 ng/mL) and ethyl decanoate (LOD = 66 ng/mL and LOQ = 219 ng/mL) with the lowest LOD and LOQ when using Rappaport-Vassiliadis Soya peptone (RVS) broth media and polar SPME fiber with polar GC column. The type of culture medium was found to affect the liberated VOCs. For example, 2-heptanone was not detected when S. london and S. stanley were grown in TSB but they were detected and quantified when using BHI as growth media. Also, 1-octanol was detected and quantified in all strains when Salmonella grown in TSB and BHI, and did not detected in all strains when RVS was used as growth media. The research has been extended to include the addition of specific enzyme substrates to the culture medium (RVS). The enzyme substrates are either commercially available or have been synthesised to allow exogenous VOC detection. The specific enzymes targeted in Salmonella were α-galactosidase, C-8 esterase and pyrrolidonyl peptidase. The enzyme substrates used are phenyl α-D-galactopyranoside, 2-chlorophenyl octanoate and L-pyrrollidonyl fluoroanilide respectively. All, except pyrrolidonyl peptidase, are known to give a positive response to Salmonella. This developed methodology was initially applied to pure cultures of S. stanley to evaluate the feasibility of the approach. The developed approach shows potential for future application in food samples to detect and identify Salmonella species in food samples of a level as low as 100 CFU/mL within a 5 h incubation at 37 ºC by the detection of the liberated VOCs. Subsequently the methodology was applied to a range of food samples (milk, cheese, eggs and chicken). It was found that all food samples were Salmonella free; however, false positive was detected due to the presence of other pathogens in the food samples. Inhibition of some of these pathogens in milk and cheese samples was achieved with the addition of 5 mg/L vancomycin and 10 mg/L of novobiocin. To improve the method specificity, it was necessary to deviate from the standard method and use Salmonella selective RVS broth in pre-enrichment step than using non selective one (BPW). This results in a successful detection of Salmonella contamination on milk samples and cheddar cheese samples. However, failed in detect Salmonella in other cheeses. Inhibition of resistant pathogens (Streptococcus salivarius ssp. Thermophilus, Lactobacillus rhamnosus and Enterococcus faecalis) using another combination of selective agents (vancomycin 10 mg/L, novobiocin 10 mg/L, erythromycin 0.75 mg/L and lithium chloride 15 g/L) failed. This study highlighted the benefits of the use of specific enzyme substrates along with antibiotics into Salmonella VOC analysis to improve the specificity of Salmonella detection method. The results of VOC analysis of specific enzymes inherent within Salmonella could be extended to develop a selective portable sensor approach to be used in food production.
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Maafi, Nasim. « Assessment of Volatile Metabolites for In Situ Detection of Fungal Decay of Wood ». Thesis, Mississippi State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10607671.
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Although incipient fungal decay of wood may be difficult to detect early, it causes a significant decrease in wood strength. Developing a reliable method of decay identification to overcome wood replacement costs by non-destructive methods is necessary. This study investigates a possibility of identifying fungal volatile organic compounds (VOCs) as means of fungal detection using solid phase micro-extraction (SPME) coupled with gas chromatography–mass spectrometry (GC-MS).
Volatile emissions from two brown rot (Gloeophyllum trabeum and Postia placenta) and two white rot (Trametes versicolor and Irpex lacteus) fungi on pine and aspen and their profiles related to wood mechanical strength and mass loss were investigated over 12 weeks. Principal component analysis of VOCs spectra differentiated volatiles from decayed and sound wood. Volatiles from two fungal species revealed distinct patterns of early and late degradation stages. SPME combined with GC-MS showed promissing results for non-destructive identification of incipient decay in wood structures.
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Westling, Magnus. « Microbial Processes and Volatile Metabolites in Cheese Detection of Bacteria Using an Electronic Nose ». Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-42412.
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Cheese is a fermented product in which bacteria contribute to different flavours and textures. In order to understand the microbial processes in cheese, it is necessary to not only look at the genomic information in bacteria. The metabolome consists of a complete collection of metabolites in a biological sample. These metabolites are small molecules with a Mr >1.5 kDa, including flavour compounds. During the ripening process of cheese, many microbiological and biochemical changes occur that give cheese a diversity of textures and flavours. Proteins that go through proteolysis and amino acid catabolism are of great importance in the development of flavour in cheese, regardless of variety. Even though techniques for measurements of metabolites have existed for a long time, there are some unique challenges by analysing of several metabolites in parallel in a biological sample that promotes different metabolic pathways. Metabolic fingerprinting is the most common approach used in metabolomics, which is based on statistical analysis that through algorithms presents differences between samples. The electronic nose is able to identify the sum of volatile metabolites in a food, which is unlike the gas chromatograph that identifies individual metabolites. The aim of this review is to evaluate the use of metabolomics of selected Enterobacteriaceae together with electronic nose technology in order to analyse possible patterns of volatile metabolites produced in soft cheese. By this we hope to evaluate potential application of this approach in food quality control and microbial contamination screening. The pilot study was done together with the center for AASS, Örebro University where bacteria were analysed using the electronic nose NST3320. The study showed that it is possible to discriminate between Enterobacteriaceae, Staphylococcus aureus and cheese-associated bacteria, but also between the Enterobacteriaceae species Escherichia coli, Hafnia alvei and Klebsiella neumoniae. It is important to consider the gas sensors gradually lose their ability to detect substances after continual use, in which they need to be replaced with new gas sensors. Further, data processing requires special knowledge and can be hard to handle if the expertise is lacking. We believe that there is evidence that metabolomics together with the electronic nose have future prospects in terms of quality control and microbial contamination screening.
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Mayeux, Bruno. « Ecologie microbienne et métabolisme associé : étude de l'eau interstitielle et de la roche argileuse du Callovo-Oxfordien dans le Laboratoire de Recherche Souterrain de l’Andra (Meuse/Haute-Marne) ». Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4783/document.
Texte intégralRésumé :
Dans le cadre des recherches de l'ANDRA sur le confinement en couche géologique profonde de déchets radioactifs, une étude microbiologique a été menée sur l'eau interstitielle et l'argile du Callovo-Oxfordien (–490m, 165 millions d'années). Deux types d'études ont été menés, culturale et moléculaire.Malgré différentes tentatives d'extractions, et comme pour les études antérieures effectuées, aucun ADN n'a pu être extrait au cours de ce travail. Par contre, une approche culturale a permis de mettre en évidence la présence d'une microflore peu dense mais viable et métaboliquement assez variée : neuf espèces aérobies dont quatre facultatives et deux anaérobies strictes, de différents types métaboliques : sulfato-réducteur, réducteur de Fe(III), fermentaire et oxydation complète des substrats en CO2. Au vu des disponibilités in-situ en sources de carbone (SC) et d'énergie nécessaires à la croissance bactérienne, la production d'acétate et autres acides gras volatils ainsi que la production d'hydrogène pourraient potentiellement être actifs dans le Cox. L'étude des produits du métabolisme a permis d'identifier plusieurs agents biotiques (dont H2S) ayant potentiellement une activité biocorrosive. Par ce travail il apparait fondamental que la composante biologique soit prise en compte dans la conception du stockage, afin notamment d'éviter ou de limiter tout apport de matière organique exogène à la formation argileuse. Cette prise en compte biologique apparait cruciale pour tenter de restreindre le réseau trophique bactérien à ces conditions initiales, celles qui sont potentiellement présentes sur le site de stockage, qui concernent les seules SC et d'énergie autochtonesIn the framework of research of ANDRA about reversible deep geological radioactive waste, a microbiological study was conducted on pore water and Callovo-Oxfordian clay layer (-490m and 165 million years). Two types of studies were conducted, a cultural approach and a molecular approach.Despite various attempts of extraction, and as for the previous, no DNA could be extracted in this work. However, the cultural approach has highlighted the presence of a sparse microflora but viable and metabolically quite varied: nine aerobes species including four facultative anaerobes and two strictly anaerobes. They represent different metabolic types: sulfate-reducing, iron-reducing, fermentative and complete oxidation of substrates into CO2. In view of the availability of in-situ sources of carbon and energy required for bacterial growth, the production of acetate and other volatile fatty acids as well as hydrogen production could potentially be active in the clay layer of Cox and open to varied bacterial growth.The study of metabolic products has also identified several biotic agents (including hydrogen sulfide) having a potentially biocorrosive activity. Through this work it appears that the biological component is to be taken into account in the design of radioactive waste storage, in particular to avoid or minimize any contribution of exogenous organic matter in the clay formation.This biological consideration appears crucial to attempt to restrict bacterial trophic network on these initial conditions, that is to say those that are potentially present on the storage site, that concern solely autochthonous carbon and energy sources
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Iamanaka, Beatriz Thie. « Avaliação da micobiota de grãos de café e dos metabolitos fungicos na qualidade da bebida ». [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255262.
Texte intégralRésumé :
Orientador: Neura BragagnoloTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-15T03:05:45Z (GMT). No. of bitstreams: 1 Iamanaka_BeatrizThie_D.pdf: 2489716 bytes, checksum: f28d257a6355ac8f3f2829d99d83a8be (MD5) Previous issue date: 2010
Resumo: O café passa por vários processos até chegar a ser consumido como bebida e vários fatores contribuem para a sua qualidade final, dentre eles a população microbiana presente. A contaminação dos grãos pelos microrgranismos é diversificada, envolvendo a participação de bactérias, bolores e leveduras, com a predominância de um ou outro grupo, dependendo da etapa de processamento dos grãos. Existem evidências, ainda não conclusivas de que vários fungos presentes no café podem produzir uma série de compostos que podem vir a prejudicar a qualidade da bebida. Esta pesquisa teve como objetivos analisar a micobiota dos grãos obtidos em diferentes etapas da cadeia produtiva do café; investigar a produção dos compostos voláteis produzidos pelos isolados e o impacto dos mesmos na qualidade da bebida e; avaliar sensorialmente a bebida, correlacionando com os fungos presentes. A micobiota de 41 amostras de grãos de café cru, de duas regiões produtoras do Brasil, Cerrado Mineiro/MG e Piraju/SP foram analisadas. As amostras foram coletados do pé (cereja), do solo (varreção), do terreiro (maduro, seco e passas no pé e verde) e da tulha (estocagem) e comparados dois tipos de preparo dos grãos: secagem natural e cereja descascado. As amostras de Minas Gerais apresentaram baixa infecção fúngica, as principais espécies isoladas foram Eurotium spp. e Fusarium spp. Em relação aos cafés da região de Piraju, houve uma grande diversidade de espécies isoladas, dentre àquelas mais predominantes foram Penicillium brevicompactum, Aspergillus foetidus, Penicillium crustosum e Fusarium spp. Cafés varreção e bóia (seco e passas no pé) caracterizaram-se pela alta incidência de Aspergillus foetidus, apresentando infecção superior a 16% por esta espécie e avaliação sensorial negativa. A foetidus produziu compostos voláteis, como 2-butenal, dimetilbisulfeto no meio de cultura e 1-octen 3-ol quando inoculado no café cru. Estes metabólitos são caracterizados pelo aroma desagradável de terra, mofo, estragado e pungente e foram relacionados como alguns dos compostos responsáveis pelas características negativas na análise sensorial da bebida. Foi constatado também que a presença de algumas espécies fúngicas nos grãos, mesmo em alta percentagem de infecção, não implicou necessariamente na redução da qualidade sensorial da bebida. Amostras com alta freqüência de Penicillium brevicompactum apresentaram avaliação final positiva. Esta espécie destacou-se pela produção de vários compostos voláteis com características positivas como aldeídos (2-octenal, decanal e undecanal) com aroma cítrico e herbal, e cetonas (2-nonanona, 3-nonen-2 ona, 2-undecanona e 2 pentadecanona) de aroma frutal e floral. Portanto, metabólitos produzidos durante o desenvolvimento de espécies fúngicas podem estar relacionados à introdução de características sensoriais de sabor ao café, tanto desejáveis quanto indesejáveis
Abstract: Coffee goes through several processes until consumed as a beverage and many factors contribute to its final quality, including the presence of the microbial population. The coffee beans contamination by microorganisms is diversity envolving bacteria, moulds and yeast, with predominance of one or another and is dependent of the coffee beans processing stages. There is inconclusive evidence that many fungi present in coffee can produce several volatile metabolites that can damage beverage quality. This research had the objectives to analyze the mycobiota ot the coffee beans obtained on the different stages of coffee production chain; investigate the production of volatile compounds produced by the isolates and the impact of them on the beverage quality and carry out sensory evaluation of beverage in relation to the fungal species. The mycobiota of forty-one samples of raw coffee beans from two Brazilian production areas, Cerrado Mineiro/MG and Piraju/SP were analyzed. Samples were collected from the tree (cherry beans), from the soil (¿varreção¿), from the drying yard (ripe, dry, over-ripe and immature) and drying storage (¿tulha¿) and two kinds of bean separation were compared: natural and pulped. The Minas Gerais samples had low fungal infection with the main species being Eurotium spp and Fusarium spp. In relation to the Piraju samples there was a considerable diversity of isolated species and the following were among the most predominant: Penicillium brevicompactum, Aspergillus foetidus, Penicillium crustosum and Fusarium spp. Coffee beans collected from the soil along with the over-ripe ones were a highly incidence of Aspegillus foetidus with a percent infection above 16% and a negative sensorial evaluation. Aspergillus foetidus produced volatile compounds such as 2-butenal, dimethyl dissulfite in the culture medium and 1-octen-3-ol when inoculated on the raw coffee. These metabolites were characterized by as unpleasant aroma of soil, musty, rotten and pungency and they were related as one of the responsible compounds for the negative characteristcs of the sensorial analyses.In this work the presence of some fungal species were found in the beans wich even at high levels of infection, did not necessarily result in a decrease of the sensorial evaluation. Samples with a high percentage of Penicillium brevicompactum infection had a positive final evaluation. This specie stood out from the rest due to the production of many volatile compounds with positive characteristics such as aldehydes (2-octenal, decanal and undecanal) showing citric and herbal aromas and cetones (2-nonanone, 3-nonen-2-one, 2-undecanonc and 2-pentadecanone) showing frutal and floral aroma. Therefore, metabolites produced during fungal growth can be related to the insertion of sensorial properties of flavour on coffee, both positive or negative
Doutorado
Doutor em Ciência de Alimentos
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Smith, Neil A. « Metabolism of dimethyl disulphide, carbon disulphide and other volatile sulphur compounds by chemolithoautotrophic sulphur bacteria ». Thesis, University of Warwick, 1988. http://wrap.warwick.ac.uk/106592/.
Texte intégralRésumé :
The isolation of a number of strains of bacteria able to grow on dimethyl disulphide (DMDS) and dimethyl sulphide (DNS) as sole sources of energy is described. The isolates came from diverse habitats including soil, peat, marine mud and a freshwater pond, and were morphologically and physiologically best described as thlobacilli capable of growth as Calvin cycle autotrophs on inorganic sulphur compounds, methylated sulphides or thiocyanate. One Isolate (E6) was examined in detail and analysis of its DNA showed a mean mol% G - C content of 60.5 ± 1.0 which is In the normal range of f. thioparua. Substrate oxidation kinetics indicated that methanethiol (NT), sulphide, formaldehyde and formate could be implicated as intermediates in DNDS metabolism. Growth yields in chemostat culture on DMDS Indicated that energy conservation was probably coupled to the oxidation of formaldehyde and sulphide (derived from DMDS via NT) to CO and sulphide. Further evidence for the proposed oxidation pathway of DMDS was provided by demonstration of activities of a previously uncharacterised NADH-dependent DMDS 'reductase', NT oxidase, catalase, MAD4-dependent formaldehyde and formate dehydrogenases, rlbulose 1,5 - blsphosphate carboxylase and a sulphide oxidising system. This is the first demonstration of the Isolation of organisms into pure culture that are capable of growth on DMDS as sole energy substrate. T. thioparua strain Tk-m was found to be capable of growth on carbon disulphide (CS2) and carbonyl sulphide (COS). During growth on CS2, GC/MS analysis of the chloroform-extractable volatiles from the culture medium showed the formation of COS as a transient intermediate In CS2 metabolism. Anaerobic Incubation of call suspensions with CS2 also showed the production of hydrogen sulphilde (H2S) into the headspace. The proposed pathway of CS2 metabolism by T. thioparua strain TK-m most likely involved its reductive cleavage to COS and »¿S, COS then undergoin3 similar hydrolysis to CO- and HjS. This serves as the first detailed study of microbial CS2 metabolism.
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Manzato, Lorenzo. « Marker di degradazione in semilavorati dell'industria dolciaria ». Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16827/.
Texte intégralRésumé :
L’industria dolciaria è in continua evoluzione e negli ultimi anni, accanto alle linee di produzione di dolci tradizionali, sono state introdotte linee di prodotti innovativi, confezionati in monoporzioni, definiti “merendine”. Questi alimenti sono estremamente complessi, solitamente costituiti da un impasto e da una farcitura (crema a base di cacao o nocciola, confetture di frutta). Entrambe le componenti possono subire alterazioni chimico-fisiche (raffermamento dell’impasto e ossidazione dei lipidi) e microbiologiche (sviluppo di batteri, lieviti e muffe). Nonostante alcune caratteristiche (un elevato tenore zuccherino e una bassa attività dell’acqua) garantiscano una buona stabilità, vi sono muffe e lieviti osmotolleranti ed osmofili in grado di sviluppare e degradare la matrice. Il genere Zygosaccharomyces, un lievito appartenente a questa categoria, è il principale contaminante dei prodotti di questo settore, in particolare le specie Z. bailii, Z. rouxii e Z. mellis.
In questo elaborato sono stati analizzati semilavorati dell’industria dolciaria, alcuni dei quali evidentemente degradati, con lo scopo di individuare tramite metodi analitici dei “marker metabolici”, ossia molecole volatili caratterizzate da un elevato impatto organolettico, la cui presenza è indice di contaminazione. Con l’analisi del contenuto in molecole volatili è stata riscontrata la presenza di profili aromatici caratteristici nella maggior parte dei prodotti degradati, evidenziati dall’accumulo di specifici metaboliti derivanti dal metabolismo dei lieviti (etile acetato, benzaldeide, alcol fenetilico, acetoino, 3-metil butanolo), che potrebbero essere quindi utilizzati in futuro come potenziali marker di degradazione microbica.
Questo approccio può fornire un valido aiuto nell’analisi e nel monitoraggio di diversi ingredienti da utilizzare come semilavorati dell’industria dolciaria, al fine di ottimizzare le strategie di controllo del potenziale degradativo di queste specie microbiche.
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Sharopov, Farukh [Verfasser], et Michael [Akademischer Betreuer] Wink. « Phytochemistry and bioactivities of selected plant species with volatile secondary metabolites / Farukh Sharopov ; Betreuer : Michael Wink ». Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://d-nb.info/1180502167/34.
Texte intégral
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De, Jesʹus Victor Raʹul. « The role of fungal metabolic by-products in indoor air chemistry : analytical considerations for the evaluation of poor indoor environments ». Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/30704.
Texte intégral
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Huh, Jung-Hyun. « Biochemical, Molecular and Functional Analysis of Volatile Terpene Formation in Arabidopsis Roots ». Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77151.
Texte intégralRésumé :
Plants produce secondary (or specialized) metabolites to respond to a variety of environmental changes and threats. Especially, volatile compounds released by plants facilitate short and long distance interaction with both beneficial and harmful organisms. Comparatively little is known about the organization and role of specialized metabolism in root tissues. In this study, we have investigated the root-specific formation and function of volatile terpenes in the model plant Arabidopsis.
As one objective, we have characterized the two root-specific terpene synthases, TPS22 and TPS25. Both enzymes catalyze the formation of several volatile sesquiterpenes with (E)-β-farnesene as the major product. TPS22 and TPS25 are expressed in the root in distinct different cell type-specific patterns and both genes are induced by jasmonic acid. Unexpectedly, both TPS proteins are localized to mitochondria, demonstrating a subcellular localization of terpene specialized metabolism in compartments other than the cytosol and plastids. (E)-β-Farnesene is produced at low concentrations suggesting posttranslational modifications of the TPS proteins and/or limited substrate availability in mitochondria. We hypothesize that the mitochondrial localization of TPS22 and TPS25 reflects evolutionary plasticity in subcellular compartmentation of TPS proteins with emerging or declining activity. Since (E)-β-farnesene inhibits Arabidopsis root growth in vitro, mitochondrial targeting of both proteins may fine tune (E)-β-farnesene concentrations to prevent possible autotoxic or inhibitory effects of this terpene in vivo.
We further investigated the role of volatile terpenes in Arabidopsis roots in interaction with the soil-borne oomycete, Pythium irregulare. Infection of roots with P. irregulare causes emission of the C11-homoterpene (or better called C4-norterpene) 4,8-dimethylnona-1,3,7-triene (DMNT), which is a common volatile induced by biotic stress in aerial parts of plants but was not previously known to be produced in plant roots. We demonstrate that DMNT is synthesized by a novel, root-specific pathway via oxidative degradation of the C30-triterpene, arabidiol. DMNT exhibits inhibitory effects on P. irregulare mycelium growth and oospore germination in vitro. Moreover, arabidiol and DMNT biosynthetic mutants were found to be more susceptible to P. irregulare infection and showed higher rates of Pythium colonization in comparison to wild type plants. Together, our studies demonstrate differences and plasticity in the metabolic organization and function of terpenes in roots in comparison to aboveground plant tissues.Ph. D.
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Young, Michael J. « Characterization of Volatile and Metabolite Compounds Produced by Lactococcus lactis in Low-Fat and Full-Fat Cheddar Cheese Extract ». DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/1029.
Texte intégralRésumé :
This study was conducted to compare and contrast potential aroma compounds in the headspace and small molecule metabolites produced as a result of starter culture metabolism in a full-fat and low-fat cheddar cheese model system. Past studies have indicated differences in the headspace flavor compound profiles between full-fat and low-fat Cheddar cheeses with no indication as to what compounds were produced as a result of starter culture metabolism.
Starter cultures were incubated in a Cheddar cheese extract environment that was made up of the water-soluble portion of Cheddar cheese with environmental conditions mimicking full-fat and low-fat Cheddar cheese by altering the levels of salt and milk fat globular membrane in the system. Incubation times were up to 14 days at 30°C and samples were taken at days 0, 1, 7, and 14. Headspace analysis was accomplished using solid phase micro-extraction coupled with GC-MS and small metabolites were monitored using metabolomic methods coupled with GC-MS.
Results indicate that the starter culture was responsible for an increase in the concentration of propan-2-one, heptan-2-one, 3-methylbutanal, heptanal, benzaldehyde, 2-ethylhexanal, and dimethyl trisulfide in both the full-fat and low-fat medias when compared to their respective controls. While heptanal was present at a higher concentration in the full-fat treatments compared to the low-fat treatments and 2- ethylhexan-1-ol and isothiocyanato cyclohexane were present at higher concentrations in the low-fat treatments compared to the full-fat treatments.
Principal component analysis for the headspace compounds showed a clear separation of the treatments with heptanal, p-cymene, nonan-2-one, and undecan-2-one contributing the most to the variation between the full-fat and low-fat samples, while 3- methylbutanal, heptan-2-one, benzaldehyde, 2-ethylhexan-1-ol, 2,6-dimethylheptan-4-ol, and 3-methylbutanol contributed the most to the variation between the controls and treatments.
The metabolomics data for both the bacteria and Cheddar cheese extract did not provide a clear separation between the full-fat and low-fat samples.
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Malcom, Annie, Kaitlyn Webb et W. Andrew Clark. « Profile of Volatile Fatty Acids in The Feces Of Normal And Overweight College Students ». Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/2512.
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Taylor, Tyeen Colligan, et Tyeen Colligan Taylor. « Leaf Volatile Emissions Structure Tree Community Assembly and Mediate Climate Feedbacks in Tropical Forests ». Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/623061.
Texte intégralRésumé :
The biochemistry of leaves merges the fates of trees and the atmosphere. Leaf primary metabolism cycles carbon and indirectly drives atmospheric circulation via the latent heat of transpiration. Tropical forests contain half of global forest carbon, and actively cycle carbon and energy year round, making them critical components of the coupled biosphere-climate system. Climate change threatens tropical forests with rising temperatures and increasing variability of precipitation. Their response will influence future biodiversity as well as the fate of the climate. Understanding the physiological attributes that define tropical tree responses and feedbacks to climate is a current research priority. The emission of isoprene gas from plant leaves has been demonstrated to enhance leaf tolerance to high temperatures and drought. Isoprene is a volatile secondary metabolite produced in the chloroplast by approximately one-third of plant species. While the benefits of isoprene are supported by extensive laboratory and greenhouse-based research, work has only begun to explore how the trait is integrated in plant functional strategies. Whether isoprene influences differential species performance and survival across environments has yet to be tested. An impediment to filling this clear ecological research gap has been a lack of instrumentation capable of quantifying isoprene emissions from leaves in remote field settings. The first study presented here tests the hypothesis that isoprene emission influences plant community assembly shifts across environmental gradients and through time in tropical forests. The capacity for a species to produce isoprene was associated with increased relative abundance at higher temperatures and following drought anomalies. A negative relationship with the length of seasonal drought suggests a trade-off between isoprene emission and other plant traits, such as deciduous leaf habit. The second study presents the development of a new instrument that is uniquely optimized for field-based ecological research on leaf volatiles. The new system, named PORCO (Photoionization of Organic Compounds), utilizes custom leaf cuvettes, precision light control, and an optimized commercial photoionization detector to achieve real-time detection of leaf emissions with detection limits better than 0.5 nmol m⁻² leaf s⁻¹. The third study utilizes PORCO to test hypotheses about the structuring of isoprene within plant functional strategies and across forest microenvironments in an eastern Amazonian evergreen tropical forest. The results support the role of isoprene—and potentially other volatile isoprenoids—in mitigating effects of intermittent sun exposure in the sub-canopy. Emissions are structured in a complex, multivariate manner that depends on taxonomy, leaf and wood characteristics, tree height, and light environment. The results from this dissertation work demonstrate that isoprene emission from leaves affects plant responses to climate at ecologically relevant scales. Isoprene influences climate not only by its effect on primary leaf functions, but also by directly altering atmospheric chemistry, and contributing to aerosol and cloud properties. Understanding isoprene's role in forest responses to increasing temperatures and drought will help to predict the feedbacks between forest ecosystems and climatic change.
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Rodríguez, Baixauli Ana María. « Genetic engineering of plant volatiles in fleshy fruits : pest repellency and disease resistance through D-limonene downregulation in transgenic orange plants ». Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/31655.
Texte intégralRésumé :
Los terpenos constituyen el mayor grupo de metabolitos secundarios, siendo
componentes de las glándulas de aceites esenciales, de las flores y de las resinas defensivas
de plantas aromáticas, a los que proporcionan sus aromas y sabores característicos. Los
terpenos volátiles se asocian a la defensa de muchas especies de plantas, animales y
microorganismos contra depredadores, patógenos y competidores. Por otra parte, estos
compuestos parecen servir como señales para atraer a los polinizadores y agentes dispersores
de semillas, así como a depredadores de plagas. El estudio de compuestos orgánicos volátiles
emitidos durante el desarrollo del fruto y después del desafío con diferentes agentes bióticos
puede ayudar a conocer las interacciones de los frutos carnosos no sólo con vertebrados
dispersores y depredadores, sino también con insectos y microorganismos.
Los frutos carnosos son particularmente ricos en volátiles. En los frutos cítricos, los
monoterpenos son los principales componentes de las glándulas del aceite esencial de la
cáscara (flavedo), siendo el D-limoneno el más abundante (hasta 95% en la naranja). Esta
característica hace que los cítricos sean un buen sistema modelo para el estudio de la función
de los terpenos en los frutos. La biología molecular moderna permite la realización de
experimentos para comprobar la función de terpenos por medio del uso de organismos
transformados genéticamente en los que se han manipulado los niveles de acumulación de
dichos compuestos. En este trabajo, se ha utilizado un plásmido que alberga el cDNA completo
del gen de una limoneno sintasa de cítricos (CiTMTSE1) en orientación antisentido (AS) o
sentido (S) para modificar la expresión y la acumulación de D-limoneno en plantas de naranjo
dulce (Citrus sinensis L. Osb.). La acumulación de D-limoneno en las frutas AS se redujo
drásticamente pero la acumulación de otros terpenos también se modificó, afectando a
compuestos tales como alcoholes monoterpenos, cuya concentración se incrementó en la
cáscara de las frutas. Las plantas transformadas fueron morfológicamente indistinguibles de las
plantas control (WT) y de las plantas transformadas con el vector vacío (EV).
Los frutos transgénicos fueron desafiados con un insecto plaga y con diferentes
patógenos para probar si la alteración de los niveles de acumulación de estos volátiles daba
como resultado una mejora en la respuesta del flavedo frente a plagas y patógenos. Los
machos de la mosca mediterránea de la fruta (Ceratitis capitata) expuestos a las frutas AS y EV
en ensayos en túnel de viento fueron significativamente más atraídos por el aroma de los frutos
control EV. En otros experimentos de desafío con el hongo de la podredumbre verde
Penicillium digitatum y la bacteria causante de la cancrosis de los cítricos Xanthomonas
axonopodis subsp. citri, las frutas transgénicas con un contenido reducido de D-limoneno
mostraron elevada resistencia a estos patógenos. El alto contenido en D-limoneno en la
cáscara de naranjas maduras puede ser una señal para la atracción de plagas y
microorganismos que podrían estar involucrados en la facilitación del acceso a la pulpa de los
frugívoros dispersores de semillas.
El análisis de la expresión génica global en el flavedo de las frutas transgénicas vinculó
la disminución de D-limoneno y la reducción de la expresión de genes del metabolismo de
monoterpenos con la activación de la expresión de genes implicados en inmunidad innata,
incluyendo factores de transcripción, genes de quinasas implicadas en la entrada de Ca2+ en la
célula y genes implicados en la activación de las cascadas de MAPKs, con la consiguiente
activación de la ruta de señalización de ácido jasmónico (JA), lo que provocó la activación del
metabolismo de JA y un aumentó drástico de la acumulación de JA en la cáscara de la naranja
tras el desafío con P. digitatum, lo que explicaría la resistencia al menos a hongos necrotrofos
observada en las frutas.
Estos resultados indican que la acumulación de D-limoneno en la cáscara de la naranja
estaría implicada en la interacción trófica entre las frutas, insectos y microorganismos, lo cual
proporciona una visión mucho más amplia de las funciones de los terpenos en la naturaleza.
También representa una alternativa muy prometedora para incrementar la resistencia o
tolerancia de las plantas frente a patógenos y plagas.Terpenes, the largest group of secondary metabolites, are well known as constituents of essential oils, floral scents and defensive resins of aromatic plants, to which they impart their characteristic aromas and flavors. Terpene volatiles defend many species of plants, animals and microorganisms against predators, pathogens and competitors. Moreover, those compounds seem to serve as advertisements to attract pollinators and seed-dispersal agents as well as pest predators. The study of VOCs emitted during fruit development and after challenge with different biotic agents may help to determine the interactions of fleshy fruits not only with legitimate vertebrate dispersers and predators, but also with insects and microorganisms. Fleshy fruits are particularly rich in volatiles. In citrus fruits, monoterpenes are the main components of the essential oil glands of the peel, being D-limonene the most abundant one (up to 95% in orange fruits). This characteristic makes citrus a good model system for studying the function of terpenes in plants. Modern molecular biology now enable experiments to test terpenoid function by the use of genetically transformed organisms in which terpene levels have been manipulated. In this work, a plasmid harboring the complete cDNA of a citrus limonene synthase gene (CiTMTSE1) in antisense (AS) or sense (S) orientation was used to modify the expression and accumulation of D-limonene of sweet orange (Citrus sinensis L. Osb) plants. D-limonene accumulation in AS fruits was dramatically reduced but the accumulation of other terpenoids was also modified, such as monoterpene alcohols, whose concentration increased in the peel of fruits. Genetically transformed plants were morphologically indistinguishable from wild-type (WT) and empty vector (EV) control plants. Transgenic fruits were challenged against a pest and different pathogens to test whether volatile profile alteration results in an improvement in the response of the fruit flavedo against them. Males of the Mediterranean fruit fly (Ceratitis capitata) exposed to AS fruits versus EV in wind tunnel assays were significantly more attracted to the odor of EV control fruits. In separate experiments with the green mould rot of citrus fruits and citrus canker caused by Penicillium digitatum and Xanthomonas axonopodis subsp. citri, respectively, transgenic fruits with a reduced content in D-limonene showed resistance to both pathogens. High D-limonene content in mature orange peels may be a signal for attractiveness of pests and microorganisms which might be likely involved in facilitating the access to the pulp of seed dispersal frugivores. A global gene expression analysis of the flavedo of AS transgenic fruits linked the decrease of D-limonene and monoterpene metabolism to the up-regulation of genes involved in the innate immunity response, including transcription factors together with Ca2+ entry into the cell and activation of MAPK cascades, contributing to activation of jasmonic acid (JA) signaling, which triggered the up-regulation of JA metabolism and drastically increased the accumulation of JA in orange peels upon fungal challenge, explaining the resistance to necrotrophic fungi observed in AS fruits. These results indicate that limonene accumulation in the peel of citrus fruit appears to be involved in the successful trophic interaction between fruits, insects, and microorganisms and provide a much more comprehensive view of roles of terpenes in nature. It also represents a very promising alternative for increasing resistance or tolerance of plants to pathogens.
Rodríguez Baixauli, AM. (2013). Genetic engineering of plant volatiles in fleshy fruits: pest repellency and disease resistance through D-limonene downregulation in transgenic orange plants [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/31655
TESIS
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Kotani, Tetsuya. « Novel metabolic pathways for microbial oxidation of propane and ethyl t-butyl ether as volatile organic compounds ». Kyoto University, 2006. http://hdl.handle.net/2433/136493.
Texte intégralRésumé :
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第12559号
農博第1578号
新制||農||931(附属図書館)
学位論文||H18||N4175(農学部図書室)
UT51-2006-P19
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 阪井 康能, 教授 清水 昌, 教授 喜多 恵子
学位規則第4条第1項該当
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Beckett, Linda Marie. « Effects of ruminal nutrient degradability on volatile fatty acid dynamics, ruminal epithelial gene expression, and post-absorptive system ». Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/87471.
Texte intégralRésumé :
This study evaluated degradable nutrient supply effects on VFA concentrations, fluid flux and pool sizes, rumen epithelial metabolic and absorptive genes, and post-absorptive muscle and blood responses. Six ruminally cannulated Holstein heifers (BW=330 ± 11.3 kg) were used in a partially replicated Latin Square experiment with four treatments consisting of beet pulp or timothy hay and barley or corn grain. Periods were18 d with 3 d diet adaptation and 15 d of treatment. During each period, d 10 to 14 was used for in situ nutrient degradation assessment, d 16 to 18 was used for rumen fluid sampling, and d 18 was used for rumen papillae and skeletal muscle biopsies and blood sampling. In situ ruminal starch disappearance rate (barley 7.61 to 10.5 %/h vs corn 7.30 to 8.72%/h; P = 0.05) and extent of fiber disappearance (timothy hay 22.2 to 33.4 % DM vs beet pulp 34.4 to 38.7 % DM P=0.0007) differed significantly among diets. Acetate (P = 0.02) and isovalerate (P = 0.008) molar percentages (% mol) were increased by timothy hay, but propionate (P = 0.06) and valerate (P = 0.10) molar percentages were decreased. Corn increased propionate (P = 0.02) and valerate (P = 0.049) molar percentage, but decreased butyrate (P = 0.04) molar proportion. Fluid volume and fluid passage rate, and individual VFA pool sizes were not influenced by diet (P > 0.05). Four epithelial genes, two metabolic and two absorptive, had increased expression on timothy hay diets (P < 0.15). Blood acetate concentration was influenced by treatment (P = 0.067) but no other blood metabolites were. Skeletal muscle metabolic rate was significantly increased on corn diets (P = 0.023). The results of this study provide a whole-system snapshot of how the rumen environment changes on diets differing in nutrient degradability and how the post-absorptive system adapts in response.Master of Science
Over the last 50 years, dairy cattle have been bred to optimize milk production to meet growing population demands for milk and dairy products. The world population continues to grow and is projected to reach 9.7 billion people by 2050. Because of this growing population, there is an overwhelming need for dairy nutritionists to optimize the conversion of human inedible fibers into human edible food. The ruminant animal accomplishes this conversion through microbial fermentation of feedstuffs into volatile fatty acids (VFA), which account for approximately 70% of total energy available for meat, milk, and fiber production. Because rumen fermentation is a complex biochemical system, it is influenced by myriad factors including the substrate provided, the pH of the environment, and the absorptive and metabolic capacity of the rumen wall, among others. Although we understand how diet influences individual aspects of rumen fermentation, few studies have concurrently evaluated how diet influences the rumen chemical environment, the epithelium, and the resulting shifts in postabsorptive metabolism. Our study sought to understand the impacts of feedstuffs with different expected ruminally available starch and fiber supplies on these aspects of ruminant physiology. Six ruminally cannulated Holstein heifers were fed four different diets which used either beet pulp (low fiber ingredient) or timothy hay (high fiber ingredient), and ground corn (low starch ingredient) or ground barley (high starch ingredient). Heifers were fed each diet for a period of 18 days. From day 10 to day 14 of the period, nutrient degradability was assessed by incubating bags of feed in the rumen and conducting feed analysis after removed from the rumen. During the last four days of each period, rumen fluid samples, blood samples, muscle biopsies, and rumen papillae biopsies were collected. Feed analysis indicated that the starch sources differed in degradation rates (i.e. the speed of degradation) and fiber sources different in extent of rumen degradation (i.e. the percentage of feed degraded). Timothy hay caused greater concentrations of Total VFA, Total branched-chain VFA, acetate isobutyrate, and isovalerate. Timothy hay caused greater molar proportions of acetate and isovalerate. Corn caused greater molar proportions of propionate and valerate when barley caused greater molar proportions of butyrate. Rumen papillae biopsies were used to evaluate gene expression. Out of 14 genes, four were impacted by diet. Two rumen transporters responsible for the absorption of VFA had greater expression when animals were fed timothy hay diets versus beet pulp diets. Two metabolic genes also had greater expression due to timothy hay. The changes of both absorptive genes and metabolic genes is likely connected to the increased presence of VFA in the rumen. Lastly, blood acetate was increased, but there was not a specific ingredient or combination that caused the change. These results provide an overall snapshot of rumen fermentation characteristics and how changes in the rumen affect other biology.
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Kuppusami, Sharmilah. « Metabolite profiling of biological specimens using small molecular weight volatile organic compounds by proton transfer reaction time-of-flight mass spectrometry ». Thesis, University of Leicester, 2017. http://hdl.handle.net/2381/39892.
Texte intégralRésumé :
Metabolite profiling is an analytical study of metabolites that are of low molecular weight which results from normal and pathological cellular processes, using high throughput analytical technologies. This thesis documents the development of the analytical technique of proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) for the analysis of small molecular weight volatile organic compounds (VOCs) in different biological specimens. The work explored the challenges associated with sampling, analysis, and metabolite profiling and identification in microbiology and clinical studies. Initial work focused on the VOCs produced in the headspace of ten Clostridium difficile ribotypes in an attempt to metabolically profile C. difficile at the ribotype level. The C. difficile ribotypes were successfully distinguished from one another. The metabolite profiles suggested that VOC profiling may provide a useful indicator for the identification of the ribotypes. The PTR-ToF-MS system was applied to two clinical trials. The first was a genitourinary clinical trial of patients with sexually transmitted infections (STI), which explored the VOCs emitted from vaginal, cervical and throat swabs to support the hypothesis that metabolite profiling has the potential to identify the presence of infection. The second involved the analysis of exhaled breath to examine the VOCs in the breath of individuals with ovarian cancer (7 female cancer patients, 12 healthy female controls, 5 female with benign cysts) using offline breath collection technique. The premise is that the VOCs in the breath are representative of the VOCs in blood; therefore specific VOCs may be produced in the body caused by tumour cells and these can be detected in breath. Within these applications, the PTR-ToF-MS was able to demonstrate that metabolite profiles are promising biomarkers for disease/infection identification, as well as providing information of cell mechanism and alterations in cells.
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Costa, Carina Filipa Pedrosa da. « Volatile exometabolone analysis of Aspergillus niger and search for molecular biomarkers pattern ». Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14864.
Texte intégralRésumé :
Mestrado em Biologia Aplicada - Microbiologia Clínica e AmbientalFungal infections have greatly increased in risk populations, namely in immunocompromised patients, probabily because the diagnosis of fungal infections is delayed. Microbial metabolomics arises as a powerful feature screening the metabolites produced by microorganisms. It provides information regarding the state of biological organisms which can be used as a diagnostic tool for diseases through fungal metabolites pattern. Thus, this research aimed to in-depth study of the Aspergillus niger exometabolome, in order to establish a targeted metabolomic pattern that characterizes A. niger. A methodology based on headspace-solid phase microextraction combined with comprehensive two-dimensional gas chromatography coupled to mass spectrometry with a high resolution time of flight analyser (HS-SPME/GC×GC-ToFMS) was used. A. niger exometabolome was analysed in different growth conditions: temperature (25 and 37 °C), incubation time (3 and 5 days), and culture medium (solid and liquid medium). A. niger exometabolome included 430 metabolites, distributed over several chemical families, being the major ones alcohols, aldehydes, esters, hydrocarbons, ketones and terpenoids. Differences among volatile metabolites produced under different growth conditions were observed, being the major relative abundance determined for 5 days of growth, at 25 °C, using solid medium. These results indicated the high complexity of A. niger exometabolome. A subset of 44 metabolites, which were present in all previously tested growth conditions, was defined as the A. niger targeted metabolomic pattern. This pattern may be used in detection of fungal infections by this specie and be further exploited to fungal infections diagnosis. Furthermore, this subset of metabolites was compared with samples of Candida albicans (yeast) and Penicillium chrysogenum (filamentous fungi), and Partial Least Squares Discriminant Analysis (PLS-DA) was applied. The results clearly showed that this metabolites subset allowed the distinction between these microorganisms. In order to validate the PLS-DA model, permutation test was applied, and a statistically significant model for 44 metabolites was obtained with a predictive Q2 capability of 0.70 for A. niger. When the subset of compounds were reduced to 16 (obtained by Variables Importance in Projection (VIP) parameter), the obtained model had a predictive Q2 capability of 0.86 for A. niger, which was significantly higher, being more robust than the previous. The decrease of 44 to 16 metabolites, reduced the require analysis time and the conditions used were similar to the conditions used in clinical context, (solid medium, at 25 °C and ca. 1 week). However, in this study was possible to reduce the time for 3 days. In conclusion, these 44 volatile molecular biomarkers could be useful for diagnosis of fungal infections, and they can even be further exploited in clinical context.
As infeções fúngicas têm aumentado bastante em populações de risco, nomeadamente em pacientes imunocomprometidos, provavelmente devido a atrasos no diagnóstico das infeções fúngicas. A metabolómica microbiana surge como um poderoso recurso de triagem dos metabolitos produzidos por microrganismos. Esta fornece informações sobre o estado de organismos biológicos, que podem ser usados como uma ferramenta de diagnóstico para infeções fúngicas através de um padrão de metabolitos fúngicos. Assim, este trabalho teve como objetivo estudar em profundidade o exometaboloma de Aspergillus niger, a fim de estabelecer um padrão metobolómico alvo que caracterize o A. niger. Foi usada uma metodologia baseada em microextração em fase sólida no espaço de cabeça combinada com cromatografia de gás bidimensional abrangente acoplada a espectrometria de massa por tempo de voo (HS-SPME / GC×GC-ToFMS). O exometaboloma de A. niger foi analisado em diferentes condições de crescimento: temperatura (25 e 37 °C), tempo de incubação (3 e 5 dias) e meio de cultura (meio sólido e líquido). O exometaboloma do A. niger incluiu 430 metabolitos, distribuídos em várias famílias químicas, sendo os mais importantes os álcoois, aldeídos, ésteres, cetonas, hidrocarbonetos e terpenos. Observaram-se diferenças entre os metabolitos voláteis produzidos em diferentes condições de crescimento, sendo a maior abundância relativa determinada para os 5 dias de crescimento, a 25 °C, utilizando meio sólido. Estes resultados indicaram a alta complexidade do exometaboloma do A. niger. Um subconjunto de 44 metabolitos, que estavam presentes em todas as condições de crescimento testadas, foi definido como um padrão metabolómico alvo para o A. niger. Este padrão pode ser usado na deteção de infeções fúngicas por esta espécie e ser futuramente explorado para diagnóstico de infeções fúngicas. Além disso, este subconjunto de metabolitos foi comparado com amostras de Candida albicans (levedura) e Penicillium chrysogenum (fungo filamentoso), e a análise discriminante com método dos mínimos quadrados parciais (PLS-DA) foi aplicada. Os resultados mostraram claramente que este subconjunto de metabolitos permitiu distinguir estes microrganismos. Para validar o modelo do PLS-DA, o teste das permutações foi aplicado, e um modelo estatísticamente significante para os 44 metabolitos foi obtido com uma capacidade preditiva Q2 de 0.70 para o A. niger. Quando o subconjunto de compostos foi reduzido para 16 (obtidos pelo parâmetro Importância da Variável na Projeção (VIP)), o modelo obtido teve uma capacidade preditiva Q2 de 0.86 para o A. niger, que foi significantemente superior, sendo mais robusto que o anterior. A diminuição de 44 para 16 metabolitos, reduziu o tempo de análise necessário e as condições utilizadas foram semelhantes às condições utilizadas em contexto clínico, (meio sólido e 25 °C e aproximadamente 1 semana). No entanto, neste estudo, foi possível reduzir o tempo para 3 dias. Em conclusão, estes 44 biomarcadores moleculares voláteis poderão ser úteis para o diagnóstico de infeções fúngicas, e podem ser explorados em contexto clínico.
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Valdetara, F. « STUDY OF THE VOLATILE PHENOL METABOLISM AND ROLE OF SO2 AS STRESS AGENT IN BRETTANOMYCES/DEKKERA BRUXELLENSIS UNDER WINE CONDITIONS ». Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/541053.
Texte intégralRésumé :
Biological spoilage of wine arises from yeasts and bacteria metabolic activity. Brettanomyces/Dekkera bruxellensis, one of the main contaminating yeast, is able to produce unpleasant compounds, such as vinyl and ethyl phenols (VPs). These off-flavors define the so called “Brett” character. Two enzymes, the cinnamate decarboxylase (CD) and the vinylphenol reductase (VPR), are involved in the spoilage activity. Sulphur dioxide (SO2) is the most common additive used to prevent and/or control microbial contamination in many foods, but decreasing its use is advisable both for limiting the detrimental cumulative effects on human health and improving the sustainability in winemaking. The first aim of this study was to provide a certain identification of the VPR enzyme, by cloning the gene in a species not producing ethyl phenols, such as Saccharomyces cerevisiae. The role of this enzyme in the conversion of 4-vinyl guaiacol into 4-ethyl guaiacol was proven by the expression, of a biologically active form of the heterologous protein. A VPR specific activity of 9 ± 0.6 mU/mg is found in crude extracts of transformed clones of S. cerevisiae. A his-tag purification approach allowed to confirm the results in activity trials carried out in the enriched fraction of the protein purified from recombinant cells of S. cerevisiae; in particular, a VPR specific activity of 1.83 ± 0.03 U/mg at pH 6.0 is measured. Furthermore, the strain-dependent character of the species regarding the VP production was investigated at sequence level in 17 different D. bruxellensis strains. Since the observed polymorphism (2.3%) and the allelic heterozygosity state of the gene do not correlate with the different release in off-flavors, this could indicate that transcriptional/post-translational mechanisms might affect the final production. In addition, the expression of the two genes involved in VP production was investigated as a three-factor variation response using a Response Surface Methodology approach. As first, a proper house-keeping-gene was identified to allow the analysis of different SO2, pH and ethanol concentrations on VP production under oenological conditions. While statistical irrelevance as far SO2 lead this to not be commented as main factor affecting CD expression, the linear interaction with pH and ethanol concurr to define a significant effect (p < 0.05) on it. Considering the permissive growth condition (0 mg/L mol.SO2, pH 4.5 and 5% v/v EtOH), CD is generally downregulated. The combination of factor levels maximizing (0.83 fold-change) CD expression is: 0.25 mg/L mol. SO2, pH 4.5 and 12.5% v/v EtOH. Contrariwise, VPR expression does not seem to be influenced by any main factor nor by their interactions, but its expression is maximized (1.80 fold-change) at the same conditions calculated for CD gene. Finally, the study of the genetic mechanisms involved in the SO2 stress response of two B./D. bruxellensis strains (AWRI1499 and CBS2499) was carried out. In particular, a RNA-Seq based approach was applied on cells grew in a wine-model environment. Results confirm the ability of the species of growing in such severe conditions and suggest that the environmental adaptation observed might be due to a detoxification activity that include the sulphur metabolic process. Indeed, this metabolic strategy has been observed to be one of the main mechanisms of resistance to sulphur dioxide stress in S. cerevisiae. A relative up-regulation of genes involved in the last step of the Sequence of Reduction of Sulfate (SRS) and a high up-regulation of SSU1 gene (up to 4-fold and 47-fold in the CBS2499 and AWRI1499 strains, respectively), encoding a plasmamembrane sulfite pump, are observed.
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Grousseau, Estelle. « Potentialités de production de Poly-Hydroxy-Alcanoates (PHA) chez Cupriavidus necator sur substrats de type acides gras volatifs : études cinétiques et métaboliques ». Thesis, Toulouse, INSA, 2012. http://www.theses.fr/2012ISAT0002/document.
Texte intégralRésumé :
L’accumulation de biopolymère de réserve (PolyHydroxyAlcanoates ou PHA) par la souche Cupriavidus necator, à partir de substrats de type acides gras volatils (acide butyrique, acide propionique et acide acétique) a été étudiée. Elle est induite par une limitation phosphore. Les performances atteintes lors des cultures se situent parmi les meilleures de la littérature pour ce type de substrat : jusqu’à 66 g.L-1 de biomasse totale avec un pourcentage d’accumulation massique de 88% en PHB –PolyHydroxyButyrate- ou en PHB-co-HV -PolyHydroxyButyrate-co-HydroxyValerate- comportant jusqu’à 52% de motifs d’HV.Pour chaque source carbonée, une caractérisation cinétique et stœchiométrique de la souche a été réalisée en l’absence d’effets inhibiteurs dus aux substrats acides grâce à des cultures de type Fed-Batch avec des apports non limitants et non inhibiteurs en carbone. Il a été dégagé :- un taux de croissance maximal de la souche de 0,33 h-1 pour les trois acides étudiés- une relation entre vitesse spécifique de production de PHA et taux de croissance fixée par la disponibilité et les flux de production de NADPH2 avec un découplage inverse pour les taux de croissance supérieurs à 0,05 h-1 et un couplage partiel pour les taux de croissance inférieurs- un optimum de 0,35 Cmole.Cmole-1.h-1, associé à un taux de croissance de l’ordre de 0,05 h-1.- une amélioration de la production de PHB en termes de vitesses spécifiques mais également en termes de rendements si une faible croissance résiduelle est maintenueLa réponse de la souche à un excès de substrat acide a été caractérisée via l’étude de régimes transitoires induits par des pulses sur des cultures continues préalablement stabilisées en régime permanent. Il a été montré qu’en excès de phosphore, face à un brusque excès de substrat, la souche est incapable d’adapter rapidement son taux de croissance. L’excès est donc dirigé vers la production de PHA dont les voies sont plus rapidement mobilisables. En conditions limitantes de phosphore, le substrat excédentaire est utilisé pour la production de PHA. L’inhibition par les acides se traduit par une diminution des capacités de biosynthèse de la biomasse et des PHA entrainant une réduction de l’assimilation du carbone puis une diminution des rendements de conversion. D’autre part la sensibilité d’un système continu à un excès de substrat dépend du point de fonctionnement choisi : plus il est optimal en termes de vitesse, moins le système est robuste. L’acide propionique est très inhibiteur comparé aux autres acides étudiés (dès 3-4 mM contre 30-40 mM). Il n’agit pas simplement via une accumulation excessive dans le cytoplasme mais il exerce également une inhibition spécifique des voies métaboliques.Un antagonisme entre les substrats (acide acétique et butyrique) a été constaté et expliqué grâce à une analyse des flux métaboliques. L’acide acétique est assimilé préférentiellement pour produire la biomasse, l’énergie et les cofacteurs nécessaires à la production de PHA, alors que l’acide butyrique est utilisé pour la synthèse de PHB. La proportion maximale d’acide acétique admise dans l’alimentation en fonction des conditions fixées en régime permanent est calculée et peut être limitée à 40% du carbone.Enfin il a été déterminé que si une croissance résiduelle est assurée grâce à un apport en phosphore, le pourcentage maximal d’HV dans le polymère dépend du taux d’acide propionique dans l’alimentation et ne peux dépasser 33 ± 5% sur acide propionique pur. Par contre, si aucune croissance résiduelle n’est assurée, il est possible de convertir l’acide propionique en motifs d’HV uniquementReserve Biopolymer (PolyHydroxyAlkanoates or PHA) accumulation by the strain Cupriavidus necator, from Volatile Fatty Acids (VFA, like butyric acid, propionic acid and acetic acid) was investigated. This production is induced by a phosphorus limitation. For this type of substrates, performances reached during cultures are among the best listed in the literature: up to 66 g.L-1 of total biomass with 88% (w/w) of PHB –PolyHydroxyButyrate- or PHB-co-HV -PolyHydroxyButyrate-co-HydroxyValerate- with a HV content up to 52 Mole%.For each carbon source, kinetic and stoechiometric characterization has been carried out thanks to Fed-Batch cultures with non-limiting and non-inhibitory carbon feed. It has been established:- a maximal growth rate of 0,33 h-1 for the three acid investigated- a relationship between specific PHA production rate and growth rate which is set by the availability and production flux of NADPH2. For growth rate above 0,05 h-1, there is an inverse coupling. For growth rate under 0,05 h-1, there is a partial coupling.- an optimum of 0,35 Cmole.Cmole-1.h-1 is associated with a growth rate of 0,05 h-1.- if a low residual growth rate is maintained, an improvement of PHB production is recorded in terms of specific production rate and yieldsThe response of the strain to an excess of acid substrate was characterized through the investigation of transient state induced by pulsed addition of substrate during continuous cultures stabilized in steady state. It was shown that in excess of phosphorus, when there is a substrate excess, the strain is unable to quickly adapt its growth rate, so the excess is directed to PHA production whose ways seem to be more easily mobilized. Under phosphorus limitation, an excess of substrate is used for PHA production. Acid inhibition results in a decrease in biomass and PHA production capacity which leads to a decrease in carbon assimilation and conversion yields. The sensitivity of a continuous system to an excess of substrate depends on the chosen operating point: the more it is optimal in terms of specific production rate, the less the system is robust. Propionic acid is highly inhibitory compared to the other acids studied (from 3-4 mM versus 30-40 mM). It does not act only via an excessive accumulation in the cytoplasm but also exerts a specific inhibition of metabolic pathways.An antagonism between substrates (acetic and butyric acid) has been established and explained thanks to the Metabolic Flux Analysis. Acetic acid is preferentially used to produce biomass, energy and cofactors for PHA synthesis, whereas butyric acid is used to product PHB. According to the conditions set during steady state, maximal content of acetic acid admitted in the feed can be calculated. It can be limited to 40% of the carbon in the feed.Finally if a growth rate is maintained thanks to a phosphorus supply, the maximal HV content in polymer is function of propionic acid in the feed and cannot exceed 33 ± 5 Mole% on pure propionic acid. Conversely, if there is no residual growth, a total conversion of propionic acid into HV is allowed
30
Sohrabi, Reza. « Biochemical and Functional Characterization of Induced Terpene Formation in Arabidopsis Roots ». Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/74938.
Texte intégralRésumé :
Plants have evolved a variety of constitutive and induced chemical defense mechanisms against biotic stress. Emission of volatile compounds from plants facilitates interactions with both beneficial and pathogenic organisms. However, knowledge of the chemical defense in roots is still limited. In this study, we have examined the root-specific biosynthesis and function of volatile terpenes in the model plant Arabidopsis. When infected with the root rot pathogen Pythium irregulare, Arabidopsis roots release the acyclic C11-homoterpene (E)-4,8-dimethylnona-1,3,7-triene (DMNT), which is a common constituent of volatile blends emitted from insect-damaged foliage. We have identified a single cytochrome P450 monooxygenase of the CYP705 family that catalyzes a root-specific oxidative degradation of the C30-triterpene precursor arabidiol thereby causing the release of DMNT and a C19-degradation product named arabidonol. We found that DMNT shows inhibitory effects on P. irregulare mycelium growth and oospore germination in vitro, and that DMNT biosynthetic mutant plants were more susceptible to P. irregulare infection. We provide evidence based on genome synteny and phylogenetic analysis that the arabidiol biosynthetic gene cluster containing the arabidiol synthase (ABDS) and CYP705A1 genes possibly emerged via local gene duplication followed by de novo neofunctionalization. Together, our studies demonstrate differences and plasticity in the metabolic organization and function of terpenes in roots in comparison to aboveground plant tissues.
Additionally, we demonstrated that the arabidiol cleavage product, arabidonol, is further modified by yet unknown enzymatic reactions into three products, which are found in root exudates. We suggested a pathway for their biosynthesis based on precursor feeding experiments and NMR analysis. Although DMNT biosynthetic genes are clustered on chromosome 4 along with several potential modification genes, we did not find a possible role of these genes in the derivatization of arabidonol. Preliminary experimental results using genetic and biochemical approaches for identifying genes involved in the modification steps are also presented. In summary, this study demonstrates an alternative route for volatile terpene formation belowground different from aboveground plant tissues via triterpene degradation and provides evidence for an unexplored triterpene catabolism pathway in Arabidopsis.
Ph. D.
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Quadri, Syeda. « Metabolomics Investigation of Glyceollins by On-Line Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry and Fungal Metabolite Identification by Thermal Desorption Analysis Coupled with Gas Chromatography-Mass Spectrometry ». ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1701.
Texte intégralRésumé :
Metabolomics is an emerging field that entails the detailed characterization of the ensemble of metabolites produced by living organisms; subfields include drug metabolism and natural environmental toxin production. The first part of the dissertation pursued metabolism of glyceollins, i.e., isoflavones produced by soybeans, that are potential cancer therapy agents. In vivo glyceollin metabolites produced in rats were investigated by on-line Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry. An odd-electron fragment ion at m/z 148, formed in violation of the even-electron rule, and diagnostic of the glyceollin backbone, was discovered. Based on this finding, a negative mode precursor ion scanning method was developed to screen for glyceollins and their metabolites from biological samples. Products of both Phase I and Phase II metabolism were identified, none of which have been previously reported. Sulfated metabolites were confirmed by accurate mass measurement, while glucuronide conjugation was confirmed by enzyme-assisted glucuronidation by rat liver microsomes. Intact GSH-glyceollin conjugates were not observed, but breakdown products of the GSH pathway, i.e., cysteinylglyceine, cysteine, and acetylated cysteine, were identified as conjugates of oxygenated glyceollins. The identification of GSH by-product conjugates was confirmed in product ion spectra acquired in the negative mode (where peptide anions, and glyceollin-bearing cleaved peptide portions were observed), as well as in the positive mode (where intact oxygenated glyceollin fragments appeared without the initially-present peptide portion). Mass spectral evidence strongly supports a metabolic pathway involving initial epoxidation of glyceollins followed by GSH addition at the epoxidation site.
The second part of the dissertation undertook the investigation of secondary metabolites called microbial volatile organic compounds (MVOCs) produced by fungi (mold) that have been reported to have adverse human health effects. MVOCs were collected onto different sorbent materials and analyzed by Thermal Desorption Analysis coupled with on-line Gas Chromatography-Mass Spectrometry. Fungal MVOCs were characterized from various simulated flooding conditions (brackish, freshwater, and saltwater) and different substrates (nutrient rich vs. low nutrient) to determine diagnostic MVOCs. Ten fungi from simulated environments were identified by genetic sequencing. Cladosporium sp. and Chaetomium sp. were cultivated and their emitted MVOCs, 3-furaldehyde and 3-(4-hydroxy-3-methoxyphenyl)-2-propenal, were proposed as diagnostic indicators of these fungi.
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Nieminen, T. (Timo). « Detection of harmful microbes and their metabolites with novel methods in the agri-food production chain ». Doctoral thesis, University of Oulu, 2009. http://urn.fi/urn:isbn:9789514290039.
Texte intégralRésumé :
Abstract
This thesis aimed at developing methods for tracking the environmental origins of microbial contaminants of the food chain. We worked on three targets: i) environmental mycobacteria ii) toxinogenic Bacillus species iii) post-harvest fungi in strawberry jam. Our aim was to develop methods for early detection of the above contaminants, which have the potential to endanger consumer health.
We developed a novel method based on 16S rRNA hybridization for tracking the reservoirs of potentially pathogenic environmental mycobacteria in piggeries and soil. From 1010 to 1012 16S rRNA molecules of environmental mycobacteria were found per gram of peat, wood shavings and straw in piggeries with a high prevalence of infections. These beddings may thus be a source of mycobacteria for pigs. We found 1010–1011 of mycobacterial 16S rRNA molecules per gram of Finnish forest soil, indicating that the soil contained 107–109 mycobacteria per gram. These numbers exceed the previous cultivation-based estimates of mycobacterial content in Finnish soils.
To elucidate the role of mastitis in the input of toxinogenic Bacillus into the dairy production chain, milks were sampled from mastitic cows. Twenty-three Bacillus isolates were screened for toxins using the sperm cell motility inhibition assay. Four of the six toxinogenic isolates found were identified as Bacillus pumilus and two as Bacillus licheniformis. The isolates produced toxic substances that were heat-stable (100 °C) and soluble in methanol, thus being of non-protein nature. The extracts prepared from the toxin-producing isolates disrupted the plasma membrane of exposed sperm cells at concentrations 1–15 μg ml-1 (B. pumilus) 20–30 μg ml-1 (B. licheniformis). The toxic action of the mastitis-associated B. licheniformis strains was similar to that of the lipopeptide lichenysin A. The genes for lichenysin synthetase were found in these strains by PCR. This study revealed that heat-stable toxin-producing strains of B. pumilus and B. licheniformis occur in milk of mastitic milking cows. They may enter the dairy production chain when milk of clinically healthy cows recovered from mastitis is sent to dairies.
Many foodborne contaminant fungi are known to produce volatile organic compounds. We investigated the suitability of such metabolites as early indicators of fungal contamination of strawberry jam. We found that volatile organic compounds commonly produced by the contaminant fungi in strawberry jam were 2-pentanone, styrene, 3-methyl-1-butanol, 1,3-pentadiene and ethanol. The results indicate that these compounds could be used to detect fungal contamination of jam.
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Koley, Somnath [Verfasser], Björn Gutachter] Junker, Jörg [Gutachter] [Degenhardt et Lars Mathias [Gutachter] Blank. « Metabolic flux analysis for biosynthesis of volatile terpenoids in model Lamiaceae plants / Somnath Koley ; Gutachter : Björn Junker, Jörg Degenhardt, Lars Mathias Blank ». Halle (Saale) : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2020. http://d-nb.info/1226764223/34.
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Saptalena, Lena Ganda [Verfasser], Ursula [Akademischer Betreuer] Telgheder et Karl [Akademischer Betreuer] Molt. « Determination of volatile metabolites of fecal contaminants in water samples by differential mobility spectrometry / Lena Ganda Saptalena. Gutachter : Karl Molt. Betreuer : Ursula Telgheder ». Duisburg, 2014. http://d-nb.info/1050933362/34.
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Reis, Leticia. « Role of ethylene in non-volatile compounds during strawberry maturation and changes in sugar metabolism during melon maturation – new studies about non-climacteric fruit ripening ». Universidade Estadual de Ponta Grossa, 2018. http://tede2.uepg.br/jspui/handle/prefix/2757.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Em virtude da respiração e, produção e resposta ao etileno, os frutos carnosos foram classificados em climatéricos e não-climatéricos. De maneira genérica, os frutos climatéricos são aqueles cujo amadurecimento ocorre concomitantemente a um pico na respiração e aumento na produção de etileno; são extremamente responsivos ao etileno exógeno; e são conhecidos por serem capazes de completar a maturação mesmo destacados da planta mãe, já que o ponto de maturação fisiológica antecede o ponto de colheita. Já os frutos não-climatéricos, não apresentam pico respiratório e de produção de etileno durante a maturação; não respondem ao etileno exógeno na maioria dos casos; e não são capazes de amadurecer destacados da planta mãe, já que o ponto de maturação fisiológica coincide com o ponto de colheita. Estudos realizados principalmente em tomate, modelo climatério de fruto de polpa, geraram informações importantes sobre a produção, percepção e transdução de sinal do etileno, bem como, sua influência na mudança de cor, sabor, textura e aroma dos frutos, o que possibilitou o desenvolvimento de tecnologias de produção, colheita e pós-colheita mais eficientes. Todavia, no amadurecimento de frutos não-climatéricos, embora muitos trabalhos estejam sendo realizados, ainda existem muitas questões a serem elucidadas. Dentre os frutos nãoclimatéricos, o morango (Fragaria ananassa L Dutch) é o sistema mais estudado para o entendimento do papel do etileno na regulação da maturação, incluindo vários genes relacionados com a maturação já caracterizados. Recentemente, o melão (Cucumis melo L.), vem surgindo como uma nova proposta de modelo de estudos devido a presença de variedades climatéricas e não-climatéricas, possibilitando a comparação entre frutos modelo da mesma espécie. Assim, no presente estudo, frutos de morango var ‘Albion’ ligado à planta mãe em quatro estágios de desenvolvimento (verde, branco, rosa e vermelho) foram imersos em três diferentes tratamentos (Ethephon - composto gerador de etileno, 1-MCP - inibidor de percepção de etileno, ou água - contendo solventes e diluentes), mais um controle absoluto que não recebeu tratamento. Na maturação, todos os frutos foram colhidos e avaliados para mostrar o efeito do etileno em importantes atributos físico-químicos e compostos de qualidade não voláteis. Observou-se que o tratamento com ethefon afetou a dimensão dos frutos, a firmeza, o teor de antocianinas e o teor de alguns aminoácidos. O tratamento com 1-MCP em qualquer fase de desenvolvimento não teve efeito em nenhuma das variáveis medidas. Um segundo estudo foi conduzido com melão não-climatérico (Cucumis melo var. Amarelo) para caracterizar a expressão de importantes genes do metabolismo do açúcar durante quatro estágios de desenvolvimento do fruto (verde pequeno, verde grande, mudança de cor e totalmente maduro), pois pouco se sabe sobre o metabolismo do açúcar do melão não-climatérico e também devido à suposta ligação entre o metabolismo do açúcar e a vida de prateleira desses frutos. Os genes-alvo foram escolhidos usando informações prévias de um sequenciamento RNAseq do melão Amarelo. Os genes que codificam enzimas que consomem açúcar para fornecimento de energia foram mais expressos no início do desenvolvimento, principalmente no estágio de desenvolvimento verde grande, enquanto os genes que codificam enzimas que sintetizam açúcar e / ou direcionam esse açúcar para armazenamento foram mais expressos geralmente no estágio de mudança de cor e mantendo alta expressão em frutos maduros. Ambos estudos fornecem informações importantes sobre o amadurecimento de frutos não climatéricos que podem ser usados para melhorar as tecnologias de manejo, colheita e pós-colheita no futuro.
Based on respiration, ethylene production and ethylene response, fleshy fruit are classified as climacteric or non-climacteric. Generically, climacteric fruit are those whose maturation occurs concomitantly to a peak in respiration and increase in ethylene production; are extremely responsive to exogenous ethylene; and are able to complete ripening detached from the mother plant if physiological maturation occurs prior to harvest. On the other hand, non-climacteric fruit are classified as having no respiratory peak nor rise in ethylene production during maturation; do not respond to exogenous ethylene in most cases; and are unable to ripen detached from the mother plant, since physiological ripeness must coincide with the time of harvest. Studies conducted mainly on tomatoes, a model climacteric fruit, generated important information on ethylene production, perception, and signal transduction, as well as their influence on change of color, flavor, texture and aroma, which allowed the development of more efficient production, harvesting and post-harvest technologies. However, in the maturation of non-climacteric fruits, although much research has been conducted, there are still many questions to be elucidated. Among the non-climacteric fruits, strawberry (Fragaria ananassa L. Dutch) is the most studied system for understanding the role of ethylene in ripening regulation with several genes related to ripening already characterized. Recently, the melon fruit (Cucumis melo L.), is emerging as a new model to study fruit ripening due to the presence of climatic and non-climatic cultivars, allowing the comparison of results among model fruit of the same species. Therefore, in the present study ‘Albion’ strawberry fruit on the plant at four developmental stages (Green, White, Pink and Red) were immersed in three different treatments (Ethephon – an ethylene-generating compound, 1-MCP - an ethylene perception inhibitor, or Water - containing solvents and diluents), plus one absolute control that received no treatment. At ripeness all fruit were harvested and evaluated to show the effect of ethylene on important physical-chemical attributes and non-volatile quality compounds. Ethephon treatment was observed to affect fruit dimension, firmness, anthocyanins and amino acid content. Treatment with 1-MCP at any developmental stage had no effect on any of the variables measured. A second study was conducted with a non-climacteric melon fruit (Cucumis melo cv. ‘Yellow’) to characterize the expression of important sugar metabolism genes during four fruit development stages (small green, large green, color change and full ripe) to relate sugar metabolism of non-climacteric melon with possible linkage to sugar metabolism and shelf life of these fruits. The target genes were choosen using previous information from a RNAseq sequencing of ‘Yellow’ melon. Genes encoding enzymes that metabolise sugar for energy were observed to be more expressed early in development at the large green development stage, while genes encoding enzymes that synthesize sugar and/or direct this sugar to storage were observed to be expressed later in development, at the color change and full ripe stages. Both studies provided important information about non-climacteric fruit ripening that can be used to improve management, harvest and post-harvest technologies in the future.
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Silva, Simone Vieira da. « Prospecção de compostos orgânicos voláteis e seus efeitos na auto-regulação fisiológica em cianobactérias ». Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/9/9141/tde-12122017-124445/.
Texte intégralRésumé :
Apesar dos diversos estudos sobre a presença de cianobactérias e a correlação entre fatores ambientais que influenciam ou desencadeiam florações, é ainda incipiente a informação sobre o controle fisiológico e bioquímico da produção de metabólitos secundários, cianotoxinas e compostos orgânicos voláteis (COVs) nestes organismos. Os COVs mais comumente encontrados em cianobactérias são a geosmina e o 2- metil-isoborneol, compostos que resistem ao tratamento convencional da água, causam mau cheiro e alteram seu gosto, além de bioacumular em peixes e moluscos. Estudos sobre possíveis sistemas de competição (alelopatia) entre linhagens de cianobactérias, ou entre elas e outros organismos, podem contribuir para elucidação do papel da produção de COVs por cianobactérias. Dessa forma, os objetivos deste projeto foram (i) prospectar a produção de COVs e seus efeitos na auto-regulação fisiológica em cianobactérias mantidas em laboratório; e (ii) desenvolver um método analítico, por microextração em fase sólida (SPME) e cromatografia em fase gasosa com detecção por espectrometria de massas (GC-MS), para a determinação destes compostos. Foram realizados ensaios para avaliar os perfis de produção dos COVs em duas linhagens de M. aeruginosa em diferentes fases de crescimento, sob diferentes intensidades luminosas (50, 150 e 250 ?µmol.fótons.m-2.s-1) e também ao longo do ritmo circadiano, avaliando a influência dos períodos claro e escuro. Para avaliar efeitos alelopáticos, exsudatos de uma linhagem de M. aeruginosa produtora de microcistinas foram testados em culturas de outra linhagem de M. aeruginosa não produtora de toxinas por meio de técnicas tradicionais de cultivo com monitoramento do crescimento. Na análise da produção de COVs, por GC-MS, observou-se que se destacam, majoritariamente, os compostos α-ciclocitral, β-ciclocitral e β-ionona, sendo o β-ciclocitral o mais abundante, em todas as condições testadas, para as ambas as linhagens estudadas. A linhagem não toxigênica, no entanto, apresentou produção mais elevada de todos os compostos identificados. Dentre as intensidades luminosas testadas, a intensidade de 250 µmol.fótons.m-2s-1 foi a que apresentou a maior taxa de crescimento para a linhagem LTPNA 08 e relação negativa entre o aumento da irradiância e a produção de β-ciclocitral. Foram identificadas, também, variações na produção dos compostos α-ciclocitral, β-ciclocitral e β-ionona nas linhagens ao longo do ritmo circadiano, sendo as maiores concentrações encontradas no período escuro. Observou-se morte celular e redução na produção de COVs 24 horas após adição de exsudatos pertencentes à linhagem de M. aeruginosa toxigênica em cultivos da linhagem não-toxigênica. Sendo assim, pode-se inferir que a produção dos COVs pode sofrer alterações qualitativas e quantitativas dependendo do estímulo ambiental presente, tanto por interações bióticas (com outros organismos e ritmo circadiano), quanto por fatores abióticos (intensidade luminosa).There are several studies on the presence of cyanobacteria and the correlation between environmental factors that may influence or trigger blooms. However, information concerning the physiological and biochemical control of the production of secondary metabolites, toxins and volatile organic compounds (VOC) by cyanobacteria is poorly understood. Geosmin and 2-methyl-isoborneolare are commonly found VOC in cyanobacteria, they resist to conventional water treatment and can cause bad smell and taste in the final water. In addition, VOC can bioaccumulate in fish and shellfish. Studies on possible competition systems (allelopathy) either among strains of cyanobacteria or among them and other organisms such as green microalgae, may help to elucidate the role of VOC production by cyanobacteria. Thus, the main objectives of this study are: (i) prospect the production of VOCs and their effects on physiological self-regulation in cyanocrobacteria kept in the laboratory; and (ii) to develop an analytical method, by solid phase microextraction (SPME) and gas chromatography with mass spectrometry detection (GC-MS), for the determination of these compounds. The assays were carried out to evaluate the production profiles of VOCs in two strains of M. aeruginosa at different growth stages under different light intensities (50, 150 and 250 µmol.fótons.m-2.s-1) and also along of the circadian rhythm, evaluating the influence of light and dark periods. To assess allelopathic effects, exudates from a microcystin-producing strain of M. aeruginosa were tested on cultures of another non-toxin producing M. aeruginosa strain by traditional growth monitoring culture techniques. In the analysis of VOC production by GC-MS, it was observed that α-cyclocyclal, β-cyclocyclal and β-ionone compounds were the most prominent, with β-cyclocitral being the most abundant in all conditions tested, for both strains studied. The non-toxigenic lineage, however, showed higher production of all the identified compounds. Among the light intensities tested, the intensity of 250 µmol.fótons.m-2s-1 was the one with the highest growth rate and positive relation between the irradiance increase and the β-cyclocitral production. Variations in the production of the α-cyclocyclal, β-cyclocyclal and β-ionone compounds were also identified in the lines along the circadian rhythm, being the highest concentrations found in the dark period. Cell death and reduction in VOC production were observed 24 hours after addition of exudates belonging to the toxigenic M. aeruginosa lineage in cultures of the non-toxigenic lineage. Thus, it can be inferred that the production of VOCs can undergo qualitative and quantitative changes depending on the environmental stimulus present, both by biotic interactions (with other organisms and circadian rhythm) and by abiotic factors (luminous intensity).
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Lawrence, Nina. « Volatile metabolic profiling of SA Chenin blanc fresh and fruity and rich and ripe wine styles : development of analytical methods for flavour compounds (aroma and flavour) and application of chemometrics for resolution of complex analytical measurements ». Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20331.
Texte intégralRésumé :
Thesis (MSc)--Stellenbosch University, 2012ENGLISH ABSTRACT: The aroma and flavour of wine are important aspects that form the basis for consumers’ organoleptic experience of wine. Therefore, an understanding of the chemical composition of wine aroma is of major importance, to establish possible links between wine chemistry, sensory attributes and consumer preference for a product. For this purpose analytical chemistry and multivariate techniques are indispensable tools for the metabolic profiling of wine. Chenin blanc is one of the most important South African export white wine varieties. However, despite its importance, very limited profiling of Chenin blanc aroma compounds has been done and information is restricted to isolated and dated reports on a few chemical compounds only. Therefore, the overall aim of this study was to obtain an in-depth view of the volatile chemical profile of this cultivar. The first task was to perform targeted volatile metabolic profiling of the three dry and offdry Chenin blanc styles, fresh and fruity, rich and ripe unwooded and rich and ripe wooded. To this end, a new, simple and robust liquid-liquid extraction technique using dichloromethane was developed and validated for extraction of analytes prior to gas chromatography flame ionization detection (GC-FID) analysis, to quantify 57 analytes in one rapid analytical procedure. This method was applied to profile 48 Chenin blanc wines. Very successful discrimination between the three styles, using the quantified volatile compounds, was obtained with two multivariate methods. These were partial least squares regression-discriminant analysis, (PLS-DA), as well linear-DA, using best subset selection for identifying the most important variables. According to the classification models, a higher content of maturation derived, malolactic fermentation derived and wood derived compounds were predominantly characteristic of the wooded wines. Higher content of some terpenes and ethyl esters were predominantly associated with the rich and ripe unwooded style Chenin blanc wines, while the fresh and fruity style were generally characterized by high levels of acetate esters. Secondly, untargeted analysis of 21 wines was done with gas chromatography mass spectrometry (GC-MS). Mathematical chromatography, using PARAllel FACtor analysis (PARAFAC and PARAFAC2), was applied to the GC-MS data for resolution of the complex chromatographic results by multi-way modeling, and to derive unbiased multivariate classification models of the three styles. This approach provided excellent style differentiation, without the arduous task of analysis of numerous standards and setting up of calibration curves, required by the targeted approach described above. Additionally, the data generated during this study will form part of the current South African wine aroma database, which does not contain any data regarding Chenin blanc at present.
AFRIKAANSE OPSOMMING: Die aroma en geur van wyn is belangrike aspekte aangesien dit die basis vorm van die wynverbruiker se organoleptiese ervaring van die produk. Derhalwe, is ‘n deeglike kennis van die chemiese samestelling van wynaroma baie belangrik, ten einde die korrelasies tussen wynchemie, sensoriese eienskappe en verbruikersvoorkeure te bepaal. Vir hierdie doel, is die insameling van analitiese chemiese data, tesame met multi-veranderlike tegnieke om relevante inligting uit die data te onttrek, onmisbaar vir die metaboliese profilering van wyn. Chenin blanc is huidiglik een van Suid-Afrika se belangrikste uitvoer wit wynvariëteite. Ten spyte hiervan, is daar tot hede egter baie min profilering van Chenin blanc se aromakomponente gedoen en die beskikbare inligting is beperk tot geïsoleerde en verouderde navorsingsbevindinge. In die lig van bogenoemde, is die oorkoepelende motivering vir hierdie studie dus om die vlugtige chemiese komponente se profiel in Chenin blanc wyn, in diepte te bepaal. Die eerste taak was die geteikende bepaling van die metaboliese profiel van drie droë of halfdroë Chenin blanc wynstyle, nl. vars en vrugtig, ryk en ryp ongehout, asook ryk en ryp gehout. Om dit te bereik, is ‘n nuwe eenvoudige en robuuste vloeistof-vloeistof ekstraksieprosedure met dichlorometaan ontwikkel, wat analise met gaschromatografie – vlamionisasie deteksie (GC-FID) voorafgaan, om die konsentrasies van 57 komponente in een vinnige analise te bepaal. Hierdie metode is gebruik om 48 Chenin blanc wyne te profileer. Deur gebruik te maak van multi-veranderlike data analitiese tegnieke, is die gekwantifiseerde vlugtige komponente data gebruik in diskriminant analise. Baie suksesvolle onderskeid tussen die drie style, is verkry deur gebruik te maak van twee multi-veranderlike metodes, naamlik: parsiële kleinste kwadrate regressie, diskriminant analise, asook liniêre diskriminant analise. Vir laasgenoemde analise, is die seleksie van die mees belangrike veranderlikes met beste sub-groep regressie bepaal. Volgens hierdie klassifikasie modelle is ‘n hoër inhoud van veroudering-, appelmelksuurgisting- en houtverwante aroma komponente baie kenmerkend in die houtbehandelde wyne. Hoër vlakke van sommige terpene en etiel esters was kenmerkend met betrekking tot ryk en ryp ongehoute Chenin blanc style, terwyl die vars en vrugtige style meer gekenmerk was met hoë vlakke van asetaat esters. Tweedens is ‘n seleksie van 21 wyne geanaliseer deur gebruik te maak van gaschromatografie – massa spektrometrie (GC-MS) in ‘n ongeteikende metaboliese profileringsbenadering. Wiskundige chromatografiese metodes, spesifiek, parallelle faktor analise (PARAllel FACtor analysis (PARAFAC and PARAFAC2)), was voorts gebruik om komplekse chromatogramme te prosesseer met wiskundige, multi-vlak modellering. Met hierdie nie-selektiewe benadering, is ook suksesvolle klassifikasiemodelle gegenereer vir die diskriminasie tussen die drie verskillende Chenin blanc style. Die voordeel van die ongeteikende GC-MS analise, gekoppel met die data hanterings- en prosesseringsprotokols in hierdie studie gebruik, is dat die arbeidsintensiewe taak om kalibrasiekurwes op te stel vir elke individuele komponent, soos wat vereis word in die geteikende benadering, nie nodig is nie. Die data wat ingewin is gedurende hierdie studie, sal ook bygevoeg word tot ‘n bestaande Suid-Afrikaanse aroma databasis, wat tans geen data aangaande Chenin blanc wyn bevat nie.
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Sánchez, Gerardo. « Cartografiado de QTL y genes candidatos asociados a metabolitos determinantes de la calidad de fruto en melocotón ». Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/34511.
Texte intégralRésumé :
Tradicionalmente los programas de mejora del melocotón (Prunus persica (L.) Batsch) se centraron fundamentalmente en la obtención de genotipos elite de alta productividad, resistentes a plagas y patógenos, adaptados a diferentes zonas agroecológicas y que produzcan frutos de gran tamaño y buen aspecto. Como resultado, muchos de estos programas han obtenido cultivares de excelentes características agronómicas. No obstante, el mejoramiento selectivo hacia caracteres agronómicos puede ir en detrimento de la calidad organoléptica del fruto como fue demostrado en el caso de fresa y tomate donde algunos aromas se perdieron en el proceso de mejora (Klee and Giovannoni, 2011; Olbricht et al., 2008). En melocotón, la disminución de la calidad del fruto ha sido percibida por los consumidores y además es la mayor causa de insatisfacción de los mismos (Bruhn et al., 1991). Un probable consecuencia de esto puede ser el bajo consumo de melocotón en comparación con otras frutas como el plátano y la manzana (Crisosto, 2006). Estudios pioneros han establecido que el aroma es uno de los atributos principales por los cuales los consumidores juzgan la calidad del melocotón (Bruhn, 1995). El aroma está definido íntegramente por los compuestos volátiles orgánicos (VOCs) los cuales también contribuyen al sabor del fruto en combinación con azucares y ácidos orgánicos. Los volátiles del melocotón han sido estudiados con anterioridad, describiéndose un poco más de 100 compuestos incluyendo: lactonas, esteres, terpenos, aldehídos, ácidos carboxílicos y alcoholes entre otros [(Aubert and Milhet, 2007) y referencias incluidas]. La identificación de regiones génicas y genes candidatos para el control de los aromas del fruto resulta un punto fundamental para su posterior implementación en programas de mejora con el fin de obtener melocotones de mayor calidad. En este sentido nos propusimos la identificación de QTLs (del inglés ``Quantitative trait loci'') y genes candidatos involucrados en la producción de los compuestos volátiles del melocotón.
El desarrollo reciente de un conjunto técnicas analíticas de mayor potencia permitió el advenimiento de una nueva plataforma tecnológica, la metabolómica, que contempla el análisis global de los metabolitos de un organismo permitiendo abordar la evaluación de calidad de una forma más exhaustiva. Dentro de ellas, la tecnología HS-SPME-GC-MS (del inglés ``Head Space-Solid Phase Microextraction-Gas Chromatography-Mass Spectroscopy'') es actualmente el método de elección para el análisis de volátiles debido a su alta sensibilidad, reproducibilidad y robustez (Tikunov et al., 2005). Además el análisis en conjunto de los datos derivados de la metabolómica con otras tecnologías de alto rendimiento para el análisis de expresión de genes, como lo son los microarrays, ha permitido el descubrimiento de genes implicados la producción de diversos metabolitos en Arabidopsis y tomate (Mounet et al., 2009; Saito and Matsuda, 2010; Carrera et al. 2012).
En una primera instancia nos propusimos el desarrollo de una plataforma de alto rendimiento basada en HS-SPME-GC-MS para la identificación y cuantificación de compuestos volátiles en fruto de melocotón. Se ensayarán diferentes protocolos para la extracción de los compuestos volátiles con el fin de identificar el más adecuado (es decir el más sensible manteniendo la reproducibilidad y con una robustez satisfactoria). Una vez desarrollado un protocolo adecuado se analizará en paralelo la evolución de los compuestos volátiles y la expresión de genes mediante microarrays durante la maduración de diferentes genotipos de melocotón con el objetivo de identificar patrones comunes de co-regulación entre metabolitos y genes durante el desarrollo del fruto. Por último, se propuso la identificación de regiones génicas implicadas en la producción de volátiles mediante análisis de QTLs.Sánchez, G. (2013). Cartografiado de QTL y genes candidatos asociados a metabolitos determinantes de la calidad de fruto en melocotón [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34511
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Di, Santo Ludmilla Geraldo [UNESP]. « Processamento do alimento e sua influência sobre o consumo, digestibilidade e parâmetros bioquímicos de papagaios-verdadeiro (Amazona aestiva) ». Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/149784.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Estudos sobre processamento de rações e sua influência no metabolismo são escassos para psitacídeos. Desta forma, o presente estudo teve como objetivo avaliar o consumo, digestibilidade, parâmetros bioquímicos, hematológicos e radiográficos de papagaios-verdadeiro após a transição de dieta com alta gordura, baseada em girassol, para alimento balanceado para manutenção de papagaios. Esta formulação balanceada foi processada de modo a se obter três diferentes graus de cozimento do amido: Ração peletizada (PEL) - ingredientes moídos com peneira de 2mm e peletizados, com 27% de cozimento do amido; Ração extrusada baixo cozimento (EXTb) - ingredientes moídos com peneira de 2mm e extrusados com baixa transferência de energia, com 82% de cozimento do amido; Ração extrusada elevado cozimento (EXTa) - ingredientes moídos com peneira de 0,5mm e extrusados com elevada transferência de energia, com 98% de cozimento do amido. Trinta papagaios-verdadeiro adultos foram mantidos na dieta à base de girassol por 90 dias, para homogeneização do grupo e determinação dos valores basais. Posteriormente foram distribuídos em delineamento inteiramente casualizado com 10 repetições (papagaios) por tratamento (rações experimentais) e mantidos nas três dietas por um período de 160 dias. Foram determinados o consumo e a palatabilidade dos alimentos, coeficiente de digestibilidade aparente dos nutrientes, concentrações de ácidos graxos voláteis - AGVs (acético, butírico, propiônico, valérico, isovalérico e isobutírico), lactato e amônia das excretas. Ao início e final do experimento foram avaliados os parâmetros hematológicos, radiográficos e as concentrações plasmáticas de aspartato aminotransferase (AST), albumina, colesterol, triglicérides, glicose e ácido úrico. Os dados foram submetidos a análise de variância e as médias comparadas pelo teste de Tukey (P<0,05). A dieta PEL apresentou maior digestibilidade da gordura e do amido que a EXTa e EXTb (P<0,05), bem como tendência à produção de excretas com maior concentração de ácido acético e ácidos graxos de cadeia curta totais (P<0,1). Por sua vez, o girassol apresentou maior digestibilidade da matéria seca (81,3%), matéria orgânica (87,4%), extrato etéreo (97,5%), energia bruta (87,3%) e tendência de maior digestibilidade da proteína bruta (84,0%) quando comparada à médias das rações processadas (matéria seca – 67,9%, matéria orgânica – 76,7%, extrato etéreo – 89,9%, energia bruta – 74,6%, proteína bruta – 77,6%) (P<0,05). A transição de uma dieta com elevada gordura (girassol) para ração balanceada promoveu melhor perfil bioquímico sérico, com redução de glicose (242,7 para 216,0 mg/dl), triglicérides (163,9 para 111,1 mg/dl), colesterol (263,6 para 184,1 mg/dl) e AST (190,8 para 113,5 U/L) (P<0,05). O melhor aporte nutricional das rações experimentais proporcionou melhora nos parâmetros hematológicos e imunocompetência dos papagaios, com maiores concentrações de hemácias, hemoglobina, hemoglobina corpuscular média, leucócitos totais, linfócitos e monócitos, quando comparado aos valores mediante ingestão do girassol (p<0,05). Ao exame radiográfico os papagaios apresentaram redução na largura da ampulheta (coração – fígado) e na relação coração fígado (p < 0,05) após o consumo da ração processada. Foi verificado que o cozimento do amido não modificou o metabolismo dos papagaios, mas a transição de dieta com elevado teor de gordura (54,4%), como o girassol, para as rações balanceadas melhorou o metabolismo reduzindo as concentrações séricas de glicose, triglicérides, colesterol e enzima hepática, além de promover aumento de hemácias e linfócitos.
Studies on food processing and its influence on metabolism are scarce for psittacines. The present study evaluated the consumption, digestibility, serum biochemistry, and radiographic parameters of blue-fronted amazon parrots after the transition from high-fat diet, based on sunflower seed, to a balanced formulation for parrot maintenance. This formulation was processed to obtain three different degrees of starch gelatinization: Pelletized food (PEL) - ingredients ground with a 2mm sieve and pelletized, with 27% of starch cooking; Low cooking extruded feed (EXTL) - ingredients ground with 2 mm sieve and extruded with low energy transference, with 82% of starch cooking; High cooking extruded food (EXTH) - ingredients ground with 0.5 mm sieve and extruded with high energy transference, with 98% of starch cooking. Thirty adults blue-fronted amazon parrots were maintained on the sunflower seed based diet for 90 days, for homogenization of the group and determination of baseline values. Later, they were distributed in a completely randomized design with 10 repetition (parrots) per treatment (experimental food) and fed with the diets for a period of 160 days. Food consumption and palatability, apparent digestibility coefficient of nutrients, concentrations of volatile fatty acids (VFAs - acetic, butyric, propionic, valeric, isovaleric and isobutyric), lactate and ammonia of the excreta and, at the beginning and at the end of the experiment hematological, radiographic and plasma concentrations of aspartate aminotransferase (AST), albumin, cholesterol, triglycerides, glucose and uric acid were determined. The data were submitted to analysis of variance and the means compared by the Tukey's test (P <0.05). The PEL food presented higher fat and starch digestibility than the EXTL and EXTH (P<0.05) and a tendency for higher excreta concentrations of acetic acid and total short chain fatty acids (P<0.1). On the other hand, sunflower seed presented higher digestibility of dry matter (81.3%), organic matter (87.4%), fat (97.5%), crude energy (87.3%), and crude protein (84.0%) than the mean of the formulated foods (P<0.05; dry matter - 67.9%, organic matter - 76.7%, fat - 89.9%, crude energy - 74.6%, crude protein - 77.6%). The transition from a high fat diet (sunflower seed) to a balanced food improved the serum biochemical profile, reducing the concentrations of glucose (from 242.7 to 216.9 mg/dl), triglycerides (from 163.9 to 111.1 mg/dl), cholesterol (from 263.6 to 184.1 mg/dl) and AST (from 190.8 to 113.6 U/L)(P<0.05). The better nutrient profile of the formulated foods improved blood parameters and immunocompetence, with higher concentrations of hemoglobin, mean corpuscular hemoglobin, total leukocytes, lymphocytes and monocytes than when the parrots were fed with sunflower seeds (P<0.05). The radiographic exam showed a reduction in the width of the hourglass (heart - liver) and heart - liver ratio after the intake of the formulated foods (P<0.05). Food processing did not modify the metabolism of parrots, but the transition from a high-fat diet (54.4%), such as sunflower seeds, to balanced diets improved parrot metabolism reducing serum glucose, triglycerides, cholesterol and liver enzyme concentrations, improving the production of red cells and lymphocytes.
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Nascimento, Carolina Fernanda Moysés do. « Emissão de metano por bovinos Nelore ingerindo Brachiaria brizantha em diferentes estádios de maturação ». Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/10/10135/tde-19102007-134319/.
Texte intégralRésumé :
Objetivou-se avaliar a taxa de emissão de metano (CH4) pela técnica do gás traçador hexafluoreto de enxofre (SF6) e fermentação ruminal dos animais alimentados com feno de Brachiaria brizantha em diferentes estágios de crescimento. Os três tratamentos foram: I-Feno de Brachiaria brizantha com 15 dias de crescimento, II- Feno de Brachiaria brizantha com 45 dias de crescimento e III- Feno de Brachiaria brizantha com 90 dias de crescimento. Seis bovinos da raça nelore, machos, castrados, canulados no rúmen e com peso médio inicial de 402 ± 51,62 kg foram utilizados em delineamento em quadrado latino 3x3 duplicado. O experimento teve duração total de 60 dias. A adaptação às dietas durou 7 dias. No oitavo dia foram feitas coletas de fezes (5 dias) e mensuração do consumo voluntário para determinação da digestibilidade in vivo dos alimentos. No 13° dia iniciaram-se as coletas de metano (7 dias) através da técnica do gás traçador hexafluoreto de enxofre (SF6). No 20° dia foram tomadas amostras do líquido ruminal às 0, 2, 4, 6, 8 e 10 horas após a primeira alimentação para determinação do potencial hidrogeniônico (pH), N-amoniacal e ácidos graxos voláteis do líquido ruminal. A idade de corte não afetou substancialmente a concentração total ou a proporção molar dos AGV, bem como o pH, embora a concentração de N-NH3 ruminal tivesse diminuído com o avanço da idade de corte. Para os dados de digestão, apenas a digestibilidade da PB aumentou e os dados dos CNF diminuíram com o avanço da idade. A produção de metano por animal/dia não foi afetada pela idade de corte do capim. Os animais alimentados com o feno produzido com 45 dias de crescimento do capim apresentaram diminuição de consumo de MS, o que resultou em maior produção de metano por unidade de MS ingerida.The objective was to evaluate methane (CH4) emission rate by sulfur hexafluoride (SF6) tracer technique in bovines of the Nelore breed fed with Brachiaria brizantha hay in different maturation stages. The three treatments wore: I- Hay of Brachiaria brizantha with 15 days of maturation, II- Hay of Brachiaria brizantha with 45 days of maturation and III- Hay of Brachiaria brizantha with 90 days of maturation. Six bovines of the Nelore breed, males, castrated, rumen-cannulated, and 402 ± 51,62 kg of initial average weight had been used in a duplicated 3X3 latin square design. Trial lasted 54 days. The adaptation to the diets lasted 7 days. In the eighth day excrement collections (5 days) and feed sampling were done. In 13th day the methane collections were initiated using the sulfur hexafluoride SF6) tracer technique. The 20th day was used for ruminal fluid sampling at 0, 2, 4, 6, 8, and 10 hours after 1st meal for determination of pH, amoniacal-N, and volatile fatty acids in ruminal fluid. The ammoniacal nitrogen (NH3-N) concentration in treatment I was higher than II, 7,21; 2,22 mg/dl, respectively. Methane emission (g/kg DM) in treatment II was higher than I and II 23,41, 17,38, 20,02, respectively.
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Gutsche, Kerstin Amelie [Verfasser], Rudi F. [Akademischer Betreuer] Vogel, Peter [Akademischer Betreuer] Schieberle et Wilfried [Akademischer Betreuer] Schwab. « Production of volatile metabolites in model fermentations and in raw sausages by Lactobacillus sakei / Kerstin Amelie Gutsche. Gutachter : Peter Schieberle ; Wilfried Schwab ; Rudi F. Vogel. Betreuer : Rudi F. Vogel ». München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1024161404/34.
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Liu, Hung-Jyh. « Volatile fatty acid and formic acid metabolism in sheep : a thesis submitted to the University of Adelaide in fulfilment of the requirements for the degree of Master of Agricultural Science ». Title page, contents and summary only, 1990. http://web4.library.adelaide.edu.au/theses/09A/09al783.pdf.
Texte intégralRésumé :
Includes bibliographical references (leaves 59-79) Examines the metabolism of volatile fatty acid and formic acid in fed sheep. Develops a method for analysing and qualifying volatile fatty acids with special reference to formic acid in biological fluids by High-Performance Liquid Chromatography.
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Possenti, Rosana Aparecida. « Efeitos de dietas com Leucaena leucocephala com ou sem adição de Sacharomyces cerevisiae na digestão, fermentação, protozoários e produção de metano no rúmen em bovinos ». Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/74/74131/tde-18072006-135007/.
Texte intégralRésumé :
O presente trabalho teve como objetivo avaliar os efeitos do uso de leucena (Leucaena leucocephala (Lam.) de wit), em dietas para bovinos com ou sem adição de levedura (Saccharomyces cerevisiae) sobre a digestão (degradabilidade e digestiilidade), fermentação (produção de ácido graxos voláteis, amônia e metano) e população de protozoários no rúmen. Foram utilizados quatro bovinos machos mestiços, com peso vivo médio de 797 kg, canulados no rúmen em experimento com delineamento Quadrado Latino 4x4 em arranjo fatorial 2x2 com dois níveis leucena (20% e 50%) com feno de Cynodon dactylon cultivar coast-cross na presença ou ausência da levedura. Os tratamentos foram denominados: 20S = 20% de feno de leucena + 80% de de coast-cross ; 50S = 50% de feno de leucena + 50% de de coast-cross; 20L = 20% de feno de leucena + 80% de de coast-cross + 10 g de levedura; 50L = 50% de feno de leucena + 50% de de coast-cross + 10g de levedura. Os parâmetros ruminais avaliados foram: produções de ácidos graxos voláteis (AGVs); concentração de amônia; pH; produção de gás metano; taxa de passagem do líquido; degradabilidade in situ da MS, FDN e PB dos fenos de leucena e coast-cross; digestibilidade in vitro da MS dos fenos de leucena e coast-cross; contagem diferencial dos gêneros de protozoários ciliados. Houve efeitos da interação entre níveis de leucena e levedura nas dietas sobre as concentrações médias dos AGVs totais (P<0,05). As concentrações de ácido acético não apresentaram diferenças entre tratamentos. Mas as concentrações de ácido propiônico mostraram efeitos significativos para níveis de leucena na dieta e da interação N x L (P<0,05), com os maiores valores médios obtidos para o ácido propiônico em nível mais alto de leucena com levedura (19,14 mM). O aumento do nível de leucena favoreceu uma maior produção de ácido propiônico e esse efeito foi potencializado pela adição de levedura. Não houve diferenças na produção de ácido butírico nos níveis de leucena e de levedura (P>0,05) mas foram observados efeitos significativos da interação, evidenciando maiores concentrações do ácido butiríco no tratamento 20L. Não foram observadas diferenças (P>0,05), nas concentrações de amônia no rúmen, variando de 18,71 a 21,28 mg/100 mL no líquido ruminal. Houve diferença (P<0,05) na emissão de gás metano pelos animais, recebendo os diferentes tratamentos, ocorreu uma redução na produção de metano na dieta com nível elevado de leucena contendo levedura. Os valores encontrados para a cinética ruminal não foram afetados pelos tratamentos (P>0,05). A população de protozoários ciliados no rúmen sofreu alterações conforme o tratamento aplicado, tanto na concentração como na composição final da fauna, indicando um efeito associativo que ocorreu com o aumento de leucena na dieta juntamente com a levedura ou mecanismo de ação semelhante de ambos, dependendo do nível de leucena na dieta.The present work had as objective to evaluate the effect of the use of leucaena (Leucaena leucocephala (Lam.) of Wit) in diets for bovines with or without yeast addition (Saccharomyces cerevisiae) on the digestion (degradability and digestibility), fermentation (production of volatile fatty acids, ammonia and methane) and ciliate protozoa population in rumen. Four crossbred male cattle, with average body weight of 797 kg, with rumen cannula were utilized in a Latin Square assay design 4x4, in factorial arrangement (2 x 2) with two levels of leucaena (20% and 50% DM) with hay of Cynodon dactylon cv coast-cross with or without addition of yeast. The treatments had been called: 20S = 20% of leucena hay + 80% of hay of coast-cross; 50S = 50% of leucena hay + 50% of hay of coast-cross; 20L = 20% of leucena hay + 80% of hay of coast-cross + 10 g of yeast and 50L = 50% of leucena hay + 50% of hay of coast-cross + 10g yeast. The ruminal parameters evaluated were: volatile fatty acids production; ammonia concentration; pH; gas production of methane; fluid outflow; in situ degradability in situ of the DM, NDF and CP of leucena and coast-cross hays; DM in vitro digestibility of leucena and coast-cross hays and concentration and generic counting of the ciliate protozoa. It was observed effect of the interaction between leucena levels and yeast in the diets on average total concentrations of VFA. No differences were observed in the concentrations of acetic acid among the treatments. But the propionic acid concentrations had shown significant effect for levels of leucena in the diet and interaction, with higher values obtained in the high leucaena level with yeast addition (19.14 mM). The increase of the leucaena level favored a higher production of propionic acid and this effect was powed by the yeast addition. There were no differences in the butyric acid production among the treatments, but significant effect of the interaction had been observed, evidencing higher concentrations of butyric acid in the treatment 20L. No difference had been observed in the rumen ammonia concentrations, varying from 18.71 to 21,28 mg/100 mL of ruminal liquid. A reduction in the methane production was observed in the animals receiving higher level of leucena with yeast addition. The values found for the kinetic ruminal had not been affected by the treatments. There was observed alteration in the rumen protozoa population according to treatment, as much in the concentration as mainly in the final composition of the fauna, indicating to have an associative effect that occurs with the increase of leucena in the diet together with the yeast addition or occurs a mechanism of similar action of both depending on the level of leucena in the diet.
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Kistler, Martin Verfasser], de Angelis Martin [Akademischer Betreuer] [Gutachter] [Hrabé, Wolfgang [Gutachter] Wurst et Martin [Gutachter] Klingenspor. « Monitoring of volatile organic compounds in mouse breath as a new tool for metabolic phenotyping / Martin Kistler ; Gutachter : Martin Hrabé de Angelis, Wolfgang Wurst, Martin Klingenspor ; Betreuer : Martin Hrabé de Angelis ». München : Universitätsbibliothek der TU München, 2016. http://d-nb.info/1123729239/34.
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Liu, Zhenhua. « Evolutionary mechanisms of plant adaptation illustrated by cytochrome P450 genes under purifying or relaxed selection ». Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAJ008.
Texte intégralRésumé :
Les plantes produisent une remarquable diversité de métabolites pour faire face aux contraintes d’un environnement en constante fluctuation. Cependant la manière dont les plantes ont atteint un tel degré de complexité métabolique et les forces responsables de cette diversité chimique reste largement incomprise. On considère généralement que le mécanisme de duplication des gènes contribue pour une grande part à l’évolution naturelle. En absence de transfert horizontal, les gènes d’évolution récente se cantonnent généralement chez quelques espèces et sont soumis à une évolution rapide, alors que les gènes conservés et plus anciens ont une distribution beaucoup plus large et sont porteurs de fonctions essentielles. Il est donc intéressant d’étudier l’adaptation des plantes en analysant parallèlement les gènes qui présentent soit une large distribution taxonomique, soit une distribution plus restreinte, de type lignée-spécifique. Les cytochromes P450 (CYP) constituent l’une des plus vastes familles de protéines chez les plantes, présentant des phylogénies très conservées ou très branchées qui illustrent la plasticité métabolique et la diversité chimique. Pour illustrer l’évolution des fonctions des cytochromes P450 dans le métabolisme végétal, nous avons sélectionné trois gènes, l’un très conservé au cours de l’évolution, CYP715A1 et les deux autres, CYP98A8 et CYP98A9, très récemment spécialisés de manière lignée spécifique chez les Brassicaceae. Les gènes appartenant à la famille CYP715 ont évolué avant la divergence entre gymnospermes et angiospermes, et sont le plus souvent présent en copie unique dans les génomes végétaux. Ceci suggère que leur fonction est essentielle et très conservée chez les plantes à graines (spermaphytes). Sur la base d’une analyse transcriptionnelle et de l’expression du gène GUS sous le contrôle du promoteur de CYP715A1, il est apparu que ce gène est spécifiquement exprimé au cours du développement floral, dans les cellules tapétales des jeunes boutons floraux ainsi que dans les filaments lors de l’anthèse. CYP715A1 est également fortement induit dans les cellules du péricycle de la zone d’élongation racinaire en réponse au stress salin. L’induction par le sel nécessite une région promotrice située entre 2 et 3 kb en amont de la région codante (i.e ; codon START), ce qui suggère la présence d’un facteur cis à cet endroit. Afin de déterminer la fonction de CYP715A1 chez Arabidopsis thaliana, j’ai identifié deux mutants d’insertion de T-DNA par génotypage et complémenté ces mutants avec le gène natif. La perte de fonction de CYP715A1 n’a pas d’impact sur la croissance et la fertilité de la plante en conditions de laboratoire. Cependant, une analyse par microscopie électronique en transmission montre un phénotype d’intine ondulée. La perte de fonction du gène CYP715A1 a également entraîné une réduction de la taille des pétales et un défaut d’anthèse. [...]Plants produce a remarkable diversity of secondary metabolites to face continually challenging and fluctuating environmental constraints. However, how plants have reached such a high degree of metabolic complexity and what are the evolutionary forces responsible for this chemodiversity still remain largely unclarified. Gene evolution based on gene birth and extinction has been reported to nicely reflect the natural evolution. Without horizontal gene transfer, young genes are often restricted to a few species and have undergone rapid evolution, whereas old genes can be broadly distributed and are always indicative of essential housekeeping functions. It is thus of interest to study plant adaptation with parallel focus on both taxonomically widespread and lineage-specific genes. P450s are one of the largest protein families in plants, featuring both conserved and branched phylogenies. Examples of P450 properties reflecting metabolic versatility, chemodiversity and thus plant adaptation have been reported. To illustrate evolution of P450 functions in plant metabolism, we selected two P450 genes, one evolutionary conserved CYP715A1 and the second a recently specialized lineage-specific gene CYP98A9 in Arabidopsis thaliana.CYP715s evolved before the divergence between gymnosperms and angiosperms and are present in single copy in most sequenced plant genomes, suggesting an essential housekeeping function highly conserved across seed plants. Based on transcriptome analysis and promoter-driven GUS expression, CYP715A1 is selectively expressed in tapetal cells of young buds and filaments of open flowers during flower development. In addition, CYP715A1 is highly induced in the pericycle cells of the root elongation zone upon salt stress. The salt induction relies on the 2-3kb region of CYP715A1 promoter, suggesting some salt-response elements may exist in this area. To characterize the function of CYP715A1 in Arabidopsis, I identified two T-DNA insertion mutants by genotyping and confirmed by complementation with native CYP715A1 gene. Loss of function of CYP715A1 has no impact on plant growth and fertility in laboratory conditions. However, transmission electron microscopy (TEM) analysis has shown constant undulated intine phenotype in two knockout mutants and also the petal growth is significantly inhibited. These two phenotypes nicely match the native expression pattern of CYP715A1. Gene co-expression analysis suggests involvement of CYP715A1 in gibberellin (GA) metabolism under salt treatment. GAs profiling on mutant flowers also indicates reduced accumulation specific GAs. Unfortunately, no significant phenotype either related to root growth or root architecture under salt treatment can be observed. Recombinant expression of the CYP715A1 enzyme in yeast so far does not allow confirming GAmetabolism. However, metabolic profiling of inflorescences in mutants and over-expression lines, together with transcriptome analysis of the loss of function cyp715a1 mutants strongly support a CYP715A1 role in signaling, hormone homeostasis and volatile emission in agreement with the purifying selection leading to gene conservation observed in spermatophytes.[...]
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Lee, Andrew H. « Impact of cocoa (Theobroma cacao L.) fermentation on composition and concentration of polyphenols : Development of fermentation model system and utilization of yeast starter cultures ». Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/88515.
Texte intégralRésumé :
Consumption of cocoa and dark chocolate products has been associated with positive health outcomes including reduced onset of cardiovascular disease, inflammation, diabetes, obesity, and platelet disorders. Cocoa polyphenols, putatively responsible for these beneficial activities, are highly impacted by cocoa variety, agronomic effects and processing history. However, the difference in polyphenol concentration and composition between cocoa products originating from different hybrid clones (selected for high yield) or from different fermentation conditions is not fully understood. Detailed polyphenol characterization including determination of total polyphenol and total procyanidin concentrations, and qualitative and quantitative analysis of (mean) degree of polymerization was conducted. Significant differences in total polyphenol and procyanidin concentrations were observed between five genetic clones grown by the USDA-ARS Cocoa Germplasm Repository located in Mayagüez, Puerto Rico. To facilitate cocoa fermentation research in laboratories distant from cocoa harvesting sites, a laboratory-scale cocoa fermentation model system was developed in this study. This model system used dried, unfermented, cocoa beans and simulated pulp medium as the starting material. The model system supported growth of the essential succession of cocoa fermenting microorganisms and generated similar chemical changes to those observed in on-farm cocoa fermentation. Using this model system, the impact of inoculation with proprietary yeast strains Saccharomyces cerevisiae Lev F and Saccharomyces cerevisiae Lev B on cocoa polyphenol concentration and composition was evaluated. Inoculation with both yeast strains resulted in increased fermentation rate and Lev B inoculation resulted in higher total polyphenol and procyandin contents at the end of fermentation. Overall, the present work addressed the influence of cocoa variety selection and fermentation process conditions on the composition and concentration of polyphenols. These findings will contribute to continued efforts to develop cocoa products with optimized bioactivity and maximum disease preventative effects.PHD
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Sherif, Mohammed Said Zaki [Verfasser], Petr [Akademischer Betreuer] [Gutachter] Karlovsky, Richard [Gutachter] Splivallo et Andreas von [Gutachter] Tiedemann. « Effect of mycotoxin production on interactions between Fusarium species during maize infection and on the production of volatile metabolites / Mohammed Said Zaki Sherif ; Gutachter : Petr Karlovsky, Richard Splivallo, Andreas von Tiedemann ; Betreuer : Petr Karlovsky ». Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1124680535/34.
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Scheffler, Laura [Verfasser], Andrea [Akademischer Betreuer] Buettner, Andrea [Gutachter] Buettner et Jessica [Gutachter] Freiherr. « Characterization of biotransformation and excretion processes of garlic and ramson volatiles in humans : Influence on the aroma and metabolite profile of breast milk and urine / Laura Scheffler ; Gutachter : Andrea Buettner, Jessica Freiherr ; Betreuer : Andrea Buettner ». Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1189424703/34.
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MASACHCHIGE, C. N. N. NANAYAKKARAWASAM. « STUDY OF THE EFFECT OF ABIOTIC AND BIOTIC STRESS ON THE GROWTH DEVELOPMENT AND SECONDARY METABOLISM OF MEDICINAL PLANT SPECIES ». Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/168729.
Texte intégralRésumé :
Achillea collina Becker ex Rchb., a medicinal plant rich in volatile compounds, was used to study the effects of biotic and abiotic stresses over plant growth and secondary metabolism. Biotic stress was induced by Myzus persiceae Sulzer and Macrosiphoniella millefolii (De Geer ), a generalist and specialist aphid species respectively. Abiotic stress was caused by mechanical damages provoked by a pin and a specially built equipment which apply a controlled and extended pressure to the plants. Plant growth and volatile compounds emissions were evaluated in the different experimental conditions analyzed. The effect of jasmonic acid on the plant volatile fingerprint was also evaluated. The volatile emission patterns obtained in the different conditions were compared in order to have suggestions regarding the metabolic pathways activated in each situation. Furthermore pea (Pisum sativum L.) and peach (Prunus persica L. Batsch) volatile fingerprints due to M. persicae infestation were analyzed and compared to those obtained from A. collina. The comparison of the results lead to the identification of volatile compounds induced only by the aphids in all the plant species studied, suggesting the activation of a common metabolic pathway due to infestation. Preliminary molecular approach seems to confirm pytochemical data.
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Tavares, Sheila dos Santos. « Ecologia química da cana-de-açúcar : caracterização das respostas de defesa em diferentes cultivares de cana-de-açúcar ». Universidade Federal de Alagoas, 2016. http://www.repositorio.ufal.br/handle/riufal/1638.
Texte intégralRésumé :
Sugarcane plants (Saccharum sp) originates from Southeast Asia but has adapted to the climate and soil in Brazil thus become the main crop for ethanol and sugar production. The main obstacles in sugarcane production are pests and plant diseases. Amongst the various sugarcane pests, Diatrea saccharalis, are of great importance as they attack the sugarcane stalk. Upon attack, sugarcane plants combine constitutive and induced defenses in order to prevent further damage. Volatile organic compounds and secondary metabolites are two mechanisms synthetized by the plant that provides protection against herbivores. Based on the attributes, secondary metabolites have gained great interest as a tool for pest management. This study aims to identify volatile metabolites and metabolite alterations upon herbivore attack in different sugarcane cultivars in order to determine resistance. In addition, the effect of various chlorogenic acid doses on the different life stages of D. saccharalis was evaluated. Initially, two sugarcane cultivars were analyzed, SP81-3250 and SP89-1115, that are considered to be susceptible and resistant, respectively. These cultivars were acquired by the germplant bank of the Genetic Improvement Program of sugarcane at the Federal University of Viscosa (RIDESA). In addition, different material from the Saccharum Complex was used, including Saccharum officinarum, Saccharum officinarum (Caiana), Miscanthu and Erianthus, all acquired from EMBRAPA Tabuleiros Costeiros. The following behavioral assays were conducted: choice assays using wind tunnel, oviposition assays and larval performance when exposed to two plant cultivars (SP81-3250 and SP89-1115). Extraction and identification of phenolic compounds, DIMBOA and chlorogenic acid from SP81-3250 and SP89-1115 was conducted. Results from the no choice oviposition assay using D.saccaralis demonstrated a significant preference for oviposition on the SP89-1115 cultivar. There was a significant difference between the volatile profiles of the two different cultivars, which could explain the preference of D.saccaralis. The two cultivars also presented a quantitative difference of phenolic compounds present in both leaf and root tissue with and without infestation, chlorogenic acid was only detected in leaf tissue and at higher concentrations in the resistant cultivar. Feeding adult D. saccharalis with a diet containing chlorogenic acid resulted in deformation after emerging from the pupae. The various materials from the “Saccharum complex” presented a varied VOC profile. This study demonstrated that there is a difference between cultivars of sugarcane plants and their direct and indirect defense mechanisms. This provides a potential aspect that should be further explored within genetic programs of sugarcane and the development of resistant cultivars.A cana-de-açúcar (Saccharum sp.) é uma planta originária do sudeste da Ásia que adaptou-se bem ao clima e solo do Brasil, sendo a principal matéria-prima para a produção de etanol e açúcar. Um dos grandes entraves à produção de cana-de-açúcar ainda é o ataque de pragas e doenças. Dentre as pragas mais importantes para a cultura estão as que atacam o colmo e entre elas a broca-da-cana, Diatraea saccharalis. As plantas ao serem atacadas se protegem através da combinação de defesas constitutivas e induzidas que consequentemente, podem interromper a propagação do dano. Entre essas defesas está a síntese de compostos orgânicos voláteis (COVs) e a produção de metabólicos secundários tóxicos que lhes atribui proteção contra diferentes herbívoros. Este trabalho busca Identificar os metabólitos voláteis e as alterações metabólicas em diferentes cultivares de cana-de-açúcar que sejam induzidas em resposta a herbivoria, visando a busca de novas fontes de resistência. Além disso, avaliou-se o efeito de diferentes doses do ácido clorogênico sobre as diferentes fases do ciclo de vida de D. saccharalis. Primeiramente duas cultivares de cana-de-açucar foram analisadas SP81-3250 e SP89-1115 (consideradas resistente e suscetível, respectivamente). Estas foram adquiridas junto ao banco de germoplasma do Programa de Melhoramento Genético de cana-de-açúcar da Universidade Federal de Viçosa (RIDESA). Num segundo momento utilizaram-se diferentes materiais do “complexo Saccharum”, entre elas Saccharum officinarum, Saccharum officinarum (Caiana), Miscanthu e Erianthus que foram adquiridos junto a EMBRAPA Tabuleiros Costeiros. Foram realizados bioensaios de preferência em túnel de vento, comportamento de oviposição e performance larval, além de extração e identificação de compostos fenólicos, DIMBOA e ácido clorogênico nas duas cultivares SP81-3250 e SP89-1115. No teste de oviposição com chance de escolha D. saccharalis a mostrou preferência de oviposição para a cultivar suscetível SP89-1115. As diferenças encontradas entre os perfis dos COVs podem auxiliar a explicar este comportamento. As duas cultivares também apresentaram diferenças quantitativas e qualitativas nos compostos fenólicos presentes nos tecidos foliares e radiculares com e sem infestação, entre eles, o ácido clorogênico que foi detectado apenas no tecido foliar e em maior concentração na cultivar resistente. Quando adultos de D. saccharalis foram alimentados com dietas adicionadas de ácido clorogênico, estes apresentaram má formação após emergirem das pupas. Os diferentes materiais do “complexo Saccharum” apresentaram também diferenças nos perfil de COVs. Os resultados obtidos demonstram que diferentes cultivares de cana-de-açúcar possuem respostas de defesa direta e indireta distintas, apresentando-se como potencial a ser explorado e aplicado em Programas Genético de cana-de-açúcar no desenvolvimento de materiais mais resistentes.