Дисертації: "Microbial association"

1

Coutts, David A. P. "Terminal anaerobic interactions in a microbial association isolated from landfill." Thesis, University of Strathclyde, 1986. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21471.

Повний текст джерела

Анотація:

A multi-stage (5-vessel) chemostat was used to enrich and isolate from landfill a microbial association capable of dissimilating hexanoic acid (5 mM) under anoxic conditions. Two possible catabolic mechanisms existed : (i) that hexanoate was mineralised completely to carbon dioxide, although this has only been reported in sulphate-reducing bacteria (Widdel, Kohring & Mayer, 1983); and (ii) that a syntrophic association was involved in which the hydrogen produced, during hexanoate catabolism to acetate, was removed by a hydrogen-oxidising species such as a methanogen or sulphate-reducing bacterium. The multi-stage chemostat was primarily used to facilitate spatial separation of the component species of the microbial association. Examination of the formation and subsequent utilisation of metabolites, however, indicated that no such separations were attained. Sulphate concentration increases from 1,4 to 5 mM and from 5 mM to 10 mM did, eventually, result in a partial shift in the metabolic activity of the methanogens from the first vessel to the second at the final concentration. The results indicated that at least four groups of bacteria were present in the association :a hydrogen-producing acetogen, a hydrogen-utilising sulphate reducer, a hydrogen-oxidising homoacetogen and an aceticlastic methanogen. It was thus apparent that a syntrophic association was present in which in the presence of sulphate a sulphate-reducing bacterium was the dominant hydrogen utiliser whereas in the absence of this electron acceptor an association between a homo-acetogen and a methanogen dominated. Acetate was metabolised exclusively by the methanogen both in the presence and absence of sulphate. To assess the effect of a non constant dilution rate regime on the microbial association a 3-stage chemostat was constructed in which the volume was increased from an initial 310 ml in the first vessel to 700 ml in the second and finally to 1600 ml in the third. The imposed dilution rate of 0.05 h-1 in the first vessel, together with an influent sulphate concentration of 1.4 mM, resulted in the displacement of the methanogenic population. Although maximum sulphate reduction remained in the first vessel complete dissimilation of hexanoic acid was only effected in the presence of the whole association. To investigate the metabolic processes of the microbial association closed culture studies were made in which it was found that maximum rates of hexanoate degradation, by Y-oxidation, required the intervention of sulphate reduction. Since the overall pattern of metabolism remained unchanged it was apparent that the sulphate-reducing bacteria outcompeted both the methanogens and acetogens for hydrogen. The methanogenic component of the association was found to catabolise acetate to methane via an aceticlastic reaction although this mechanism was inhibited in the presence of hydrogen supplementation. Thus it was apparent that hydrogen removal to facilitate not only catabolism of hexanoate but also the subsequent dissimilation of the metabolic intermediate, acetate, was an essential requirements.

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Khan, Intisar Chowdhury. "Spreads microbiology in association with product matrix, structure and chemistry." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28996/.

Повний текст джерела

Анотація:

The overall aim of this study was to eliminate the root cause of the ‘cheese flavour’ in spread caused by four key microbes Bacillus spp, Staphylococcus spp, yeasts and moulds. The major sources of these bacteria were in the product ingredients mainly sweet cream buttermilk and skimmed milk along with environmental aerosols. The causative organisms were present in about 63% of the products and mainly ‘feed’ on the oil element of the recipe, containing high level C12 that generates the distinctive cheese flavour when broken down by bacteria. The key hurdle factor in spread preventing microbial growth is water droplet size. The spread showing cheese off flavour had a droplet size distribution of 95% <10 micron. To achieve finer droplet size distribution, trial products were made in the Scrape Surface Heat Exchanger (SSHE) over the current churning method with a distribution of droplet size 98% <5 micron. The trial product showed a 50% reduction in the generation of the ‘cheese flavour’ methyl ketones. The Staphylococcus spp cross contamination source where from personnel with direct food contact processing area. Further education on personal hygiene helped to reduce the level of Staphylococcus spp contamination in the product. The trial product from the SSHE was further challenge tested with Listeria monocytogenes over a 10 week shelf life period to evaluate product robustness against microbial growth and spoilage. The organism did not show any growth over the period of time. The liquid phase of the emulsion was further modified with various salts at different concentrations and challenged with L. monocytogenes isolated from various parts of the dairy environment. It was observed that a pH range of 5.5 or lower with added 0.063% potassium sorbate showed significant antibacterial affect compared to the nutrient enriched MPC-broth and the unsalted liquid phase of the emulsion with no added potassium sorbate. To understand L. monocytogenes survival within a dairy process, the organism was further challenged by exposure to pasteurisation heat treatments and the standard CIP cycle of acid and caustic treatment. No recovery rate of the organism was observed. Therefore it could be concluded that the contamination within the industry is more likely to be post process or environmental contamination rather than survival through the plant itself as per RASFF alert of Listeria spp outbreak in dairy. Therefore, reducing the available water in the liquid phase of the spread and achieving a <5 μm droplet size and a finer distribution within the product will be limiting factors to microbial growth. An air purifier system BAXX has reduced the level of environmental contaminants, especially yeast and mould.

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Hausdorf, Lena [Verfasser], and Dietrich [Akademischer Betreuer] Knorr. "Microbial communities and pathogens in association with vegetable-processing / Lena Hausdorf. Betreuer: Dietrich Knorr." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2012. http://d-nb.info/1023762161/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Sathiananthamoorthy, Sanchutha. "Characterisation of the urinary microbial community and its association with lower urinary tract symptoms." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10045597/.

Повний текст джерела

Анотація:

Lower urinary tract symptoms affect 2.3 billion individuals worldwide and pose a substantial burden on the quality of life. An important step in a LUTS investigation is the exclusion of a urinary tract infection with the help of nationally recommended urine tests. These tests include the routine midstream urine culture, which is regarded as the UK’s gold standard for detecting infection. Microbial confirmation of UTI stems from criteria that were originally proposed in the 1950s, following a study that examined patients with acute pyelonephritis. Whilst the clinical diagnosis of UTI is considered to be straightforward in patients that describe hallmark symptoms, notably acute frequency and dysuria, the presentation of less well-recognised LUTS may not be as straightforward to diagnose and treat. This thesis consists of original work from three specific studies. Firstly, a retrospective observational study was conducted to compare the clinical characteristics of patients describing LUTS with a suspected UTI, on the basis of their routine MSU culture findings. This study revealed the striking clinical similarities between patients with a culture result of doubtful significance that consists of multiple organisms and patients with a positive culture that represents significant bacteriuria. Secondly, an evaluation of the UK’s MSU culture was performed by comparing the microbial yield achieved with three different culture techniques. Additionally, the urinary bacterial community, represented by the cultured spun urinary cell sediment was characterised in three different cohorts. These were (i) first-visit symptomatic patients suspected to have a UTI, (ii) chronic patients with recurrent or unresolved LUTS from a previous symptomatic episode and (iii) asymptomatic individuals. Species-level microbial identification was achieved with matrix-assisted laser desorption ionisation time-of-flight mass spectrometry. The criteria used to determine significant bacteriuria and the technique employed to perform the MSU culture were identified as factors with the potential to limit the microbiological detection of UTI. Finally, following the disproved assumption of the healthy urinary tract as a sterile environment, molecular characterisation of LUTS patient and asymptomatic control urinary tract bacterial communities was achieved using 16S rRNA gene sequencing. The core bacterial taxa shared by both patient and healthy communities were determined, with Enterobacteriaceae identified as the most abundant bacterial group in patients and Streptococcus noted as the most abundant taxa in controls. Analysing unspun urine combined with concentrated urinary cell sediment significantly discriminated between the species richness of both communities. The presented original work establishes the potential significance of mixed growth urine cultures, prompting the question of their dismissal without further investigation. In addition to identifying the limitations of the UK’s MSU culture, the complex bacterial communities of asymptomatic and LUTS patients have been characterised mostly at the genus level and established as a foundation for subsequent functional characterisation to help elucidate the mechanisms involved in LUTS and UTI development.

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Le, Nhung Xuan Hong. "ASSOCIATION OF IMMUNE DYSFUNCTION WITH MICROBIAL DYNAMICS AND ABERRANT ESTROGEN METABOLISM IN REPRODUCTIVE DISORDERS." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/dissertations/1918.

Повний текст джерела

Анотація:

Chronic inflammation is associated with the pathophysiology of obstetrical disorders (e.g. preterm birth [PTB]) and gynecological diseases (e.g. endometriosis); however, the exact mechanism(s) for these conditions are unknown. Numerous immunological conditions and disease states (e.g. inflammatory bowel disease, Crohn’s disease, systemic lupus erythematomus) also disrupt the microbiome homeostasis by inducing a number of changes in the microbial flora when compared to that of healthy individuals. Furthermore, the gastrointestinal (GI) microbiome is one of the principal regulators of circulating estrogens which are known to directly impact the female reproductive disorders endometriosis and PTB. Thus, an alteration of microbial species could indicate a shift in immune balance from homeostatic to pro-inflammatory, and an aberrant estrogen metabolism that precipitates the development of disease stages in endometriosis and/or PTB. The Braundmeier-Fleming lab has developed a systems biology model that investigates the interactions between the immune system, microbial dynamics (in the GI and reproductive system) and estrogen metabolism, in women, as a potential diagnostic tool for endometriosis and PTB. This dissertation, therefore, examined how inflammation triggered by female reproductive disorders (endometriosis or PTB) alter the systemic and localization immune responses, the microbial communities in the urogenital (UG), peritoneal and GI mucosal epithelium, as well as levels of excreted conjugated estrogen. The first specific hypothesis is that inflammation associated with endometriosis alters microbial dynamics and functions that are distinct from those of non-diseased patients. Preliminary data indicated that reproductive tract microbial communities from patients with endometriosis are unique when compared to non-disease patients. Therefore, the central aims of this study are to identify the immune and microbial profiles of patients diagnosed with endometriosis and determine if an alteration of these profiles impact estrogen signaling, thus driving disease pathogenesis. Additionally, I hypothesized that surgery or hormonal therapy will temporarily restore the microbiome and estrogen levels of patients with endometriosis. Differences in systemic (blood) regulatory T cell (Treg) and T-helper 17 (Th17) cell populations (tolerant and inflammatory, respectively) were measured by flow cytometry, and the immune mediators was measured by serum cytokine levels via 10-plex-ELISA kits. Immunohistochemistry was used to identify resident Th17/Treg immune cell distribution within the endometrium and ectopic endometriotic lesions, and RORγt+/FOXP3+ transcripts within these same tissues were analyzed by real-time-qPCR. We implemented high-throughput non genomic sequencing targeting bacterial-V4 16S rRNA and robust bioinformatics analyses to characterize microbial composition/diversity within the GI (fecal swab), vaginal (vaginal swab), and UG (urine) cavities. Alterations in estrogen metabolism, parent estrogens and metabolites, in urine were analyzed via LC-MS/MS. Patients with endometriosis exhibit 1) systemic and localized inflammation within ectopic and endometrial tissues, 2) altered GI/UG microbial dynamics, 3) aberrant levels of endogenous estrogen and estrogen metabolites, 4) dampened inflammation (caused by disease) due to hormonal therapy, 5) altered bacteria populations in the gut and vaginal canal of patients with endometriosis due to hormonal therapy treatment, and 6) increased post-surgical variability in microbial community dynamics. The second specific aims examined the hypothesis that induction of endometriosis in baboons (P. Anubis) results in chronic systemic and tissue specific inflammation through regulation of Th17 and Treg populations. Further, the induction of endometriosis altered GI/UG/peritoneal cavity microbial communities that are distinct from non-diseased animals. Utilizing a non-human primate animal model of induced endometriosis allowed us to characterize factors involved at the early onset of endometriosis and throughout the disease progression. We collected samples from 8 baboons at pre-inoculation (no evidence of disease) and at 3, 6, 9, and 15 months post-induction of the disease. We found that the induction of endometriosis decreased peripheral Tregs cells while Th17 cells increased at all post-induction collections with reduced ratio of total Tregs to Th17 cells indicating systemic inflammation. Microbial community diversities as well as abundances at each sample site (GI, UG [vagina, urine] tracts and peritoneal cavity) were also altered at post-induction. These results therefore suggest that induction of endometriosis in non-human primates caused an inflammatory shift. Disease induction also resulted in altered vaginal, urinary and fecal microbial profiles, which may drive inflammation through the production of inflammatory mediators. The last specific aims studied the hypothesis that patients who deliver preterm have a systemic and placental inflammatory phenotype and abnormal estrogen levels during pregnancy that are distinct from those of patients with term delivery. Biological samples were collected at 8-12 weeks, 20-24 weeks, 32-36 weeks, at delivery and 6 weeks postpartum. Subjects with PTB showed signs of systemic inflammation with an elevation in Th17:Treg ratio, greater Th17 and lower levels of natural Tregs during the 2nd trimester, and lower inducible Tregs during the 3rd trimester and at delivery. Placental tissues from subjects with PTB also had an inflammatory immune phenotype (higher Th17) within the decidua basalis and maternal-fetal interface. Immunological shifts from tolerant to inflammatory were observed in both patient groups, but these shifts occurred early in gestation for subjects with PTB and at a later gestational age for subjects delivering at term. Levels of conjugated parent estrogens and estrogen metabolites were reduced in subjects with PTB, indicative of an abnormal production of estrogen. These analyses gave us a better understanding of the inflammatory cascade with estrogen metabolism associated with pregnancy, and how these effects are correlated with premature labor. The data from this study suggest that the levels of endogenous estrogen and estrogen metabolites of estrogen metabolism were abnormal in PTB and endometriosis disease models of inflammation compared to their respective controls. In the human and non-human primate model of endometriosis studies, we observed that both patients and baboons with endometriosis had systemic and resident inflammatory phenotypes and an alteration in mucosal microbial community dynamics compared to their respective controls. All together, our long-term goal is to identify factors from the microbiome and/or the immune system that would allow us to have early non-invasive diagnostics for endometriosis or to predict which mothers are most at risk to encounter PTB. Furthermore, it would allow us to determine whether the mucosal microbiome may be a good indicator of immune stress, and if alternative therapies can alter microbial community dynamics—thereby eliminating immune stress associated with female reproductive diseases. These findings may have a substantial impact on the obstetrical care and management of patients with endometriosis and women at risk for PTB, as well as provide evidence to support the development of novel therapeutics to treat these diseases.

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Phelps, Charlie. "Microbial diversity and function, and an exploration of bleaching in the Australian kelp Ecklonia Radiata." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2022. https://ro.ecu.edu.au/theses/2586.

Повний текст джерела

Анотація:

The kelp, Ecklonia radiata is the dominant, temperate macroalgae in the Great Southern Reef (GSR) of Australia. As a foundation species, the kelp provides a habitat for many marine organisms in the GSR benthic reef ecosystems. Macroalgae such as kelps host a dense biofilm, consisting of a compositionally and functionally diverse consortium of microbiota. The macroalgal host and its associated microbiome constitute a ‘holobiont’, where interactions can contribute towards the success and survival of both the microbial community and host. Despite the importance of E. radiata, and the tightknit relationship with its associated microbial community, describing and interpreting diversity and functionality of the microbial community is in its infancy. There is a need to further understand the dynamics of the microbial community composition and gene function, and how these vary over space and time. An understanding of natural variation is of critical importance when attempting to interpret the impact of environmental perturbations (for example, heat waves and eutrophication), which can cause shifts in microbial community composition in holobionts, and may result in dysbiosis, the proliferation of opportunistic pathogens, and eventually disease. Ecklonia radiata is documented to experience bleaching disease across its habitat range, however there are no comprehensive investigations as to the possible pathogens that are associated with E. radiata bleaching disease. Thus, the overarching aim of this thesis is to investigate the microbial diversity and function associated with E. radiata and the relationship with tissue bleaching on the kelp. Using 16S rRNA gene amplicon sequencing, Chapter 2 aimed to (1) examine the temporal and spatial variations in the bacterial community of bacterial microbiota on the kelp E. radiata, and (2) investigate the relationship between environmental drivers and the bacterial community on kelp. These analyses revealed that over large geographical distances (∼3,300 kms), kelp microbiomes differed significantly, however within regions the community structure was relatively stable. The environmental factors that were measured somewhat influenced the community structure. A persistent core microbial community was identified with the same members dominating across regions, potentially suggesting these individuals play essential roles in maintaining host health. As such, it is imperative to define the key functional roles in the E. radiata microbiome and establishing key processes that maintain kelp holobiont health. The E. radiata microbial gene function profile was then investigated through metagenome shotgun sequencing (Chapter 3). Here, I aimed to examine the functional repertoire of the bacterial community of the kelp and to identify what relationship, if any, there is between spatial (four sites in the NSW region) and temporal (seven bi-monthly time points, over a 17-month period) patterns in microbial function and associated environmental conditions. I identified several key functional pathways in the E. radiata microbiome, including pathways associated with defence response mechanisms, biogeochemical cycling and nutrient metabolism. Additionally, spatiotemporal differences in gene function composition were noted, and environmental drivers, in particular temperature, were found to influence the E. radiata microbial gene functional profile. These novel findings are fundamental in identifying the E. radiata holobiont functional processes and are critical in the understanding of the role microbes play in maintaining kelp health and the subsequent reef ecosystem. The baseline microbial community composition and functioning can be altered, this generally occurs with extreme weather conditions and or anthropological disturbances such as eutrophication. When this occurs, host associated microbial communities can shift to a depreciated state, impacting the host, potentially exacerbating opportunistic pathogens, and facilitating disease. For E. radiata some taxa have been identified to be abundant on bleached kelp compared to healthy, but their role as pathogens has not been investigated. Koch’s postulates are a series of tests that aim to establish a causative relationship between disease and pathogens and are performed through a series of inoculation studies. In marine systems, a similar series of tests have been done in a range of studies to understand the role of individual strains of bacteria in diseases of corals, sponges and macroalgae, however, the methods among studies vary slightly in the way that the inoculation treatments are performed and controlled. In Chapter 4 I aimed to explore 1) the extent of confounding effects from bacterial growth media in inoculation studies of diseases of marine benthic organisms through a literature review; 2) the effect of bacterial growth media and its components on bleaching disease. The review identified confounding factors in previous inoculation studies, based on whether the putative pathogen cells were pre-treated prior to inoculation e.g., centrifuged washed and/or filtered and if a sterile media control was incorporated in the experimental design. I found that nutrient growth media used in inoculation studies contributes to bleaching disease in E. radiata and caused a shift in the overall microbial community composition. Furthermore, the microbial community composition was substantially altered when kelps were held in aquaria, in comparison to undisturbed kelps collected from the reef. These results were summarised into a framework recommending approaches for interpretating previous inoculation studies and for future inoculation research. The recommendations for future inoculation studies include having pre-treatment methods and controls to reduce nutrient addition. It is also recommended that the microbial community composition is assessed via a method such as 16S rRNA amplicon sequencing, to identify any shifts in the microbiome when moved from the reef into the aquaria. The range of knowledge obtained from this research has widened the understanding of kelp holobiont interactions and provided invaluable data and a tool that can advise and inform researchers and managers on changes in kelp health dynamics in projected climate change conditions in the future. Hence, the key findings identified in this thesis are an important contribution for kelp conservation and identify possible concepts for restoration efforts through understanding of the E. radiata holobiont.

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Hall, G. S. "A study of the microbial association with root senescence in winter wheat following various long-established crop rotations." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355006.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Hall, Kimberlee K., Brian G. Evanshen, Kurt J. Maier, and Phillip R. Scheuerman. "Using Multivariate Statistics to Identify Patterns Association Land Use to Fecal Pollution Sources.Similar Creeks in Northeast Tennessee to Identify Patterns Associating Land Use to Fecal Pollution Sources." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etsu-works/2948.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Mari, Alfredo [Verfasser], Gunther Gutachter] Doehlemann, and Eric [Gutachter] [Kemen. "The association between overlooked microbial eukaryotes and plant holobiont: functionality and diversity / Alfredo Mari ; Gutachter: Gunther Doehlemann, Eric Kemen." Köln : Universitäts- und Stadtbibliothek Köln, 2018. http://d-nb.info/1168245842/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Mari, Alfredo Verfasser], Gunther [Gutachter] Doehlemann, and Eric [Gutachter] [Kemen. "The association between overlooked microbial eukaryotes and plant holobiont: functionality and diversity / Alfredo Mari ; Gutachter: Gunther Doehlemann, Eric Kemen." Köln : Universitäts- und Stadtbibliothek Köln, 2018. http://d-nb.info/1168245842/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Adiya, Tsolmon, Cari L. Johnson, Mark A. Loewen, Kathleen A. Ritterbush, Kurt N. Constenius, and Cory M. Dinter. "Microbial-caddisfly bioherm association from the Lower Cretaceous Shinekhudag Formation, Mongolia: Earliest record of plant armoring in fossil caddisfly cases." PUBLIC LIBRARY SCIENCE, 2017. http://hdl.handle.net/10150/626473.

Повний текст джерела

Анотація:

Caddisfly larvae construct underwater protective cases using surrounding materials, thus providing information on environmental conditions in both modern and ancient systems. Microbial bioherms associated with caddisfly cases are found in the Berriassian-Hauterivian (similar to 140-130 Ma) Shinekhudag Formation of Mongolia, and yield new insights into aspects of lacustrine paleoecosystems and paleoenvironments. This formation contains the earliest record of plant-armored caddisfly cases and a rare occurrence of microbial-caddisfly association from the Mesozoic. The bioherms are investigated within the context of stratigraphic correlations, depositional environment interpretations, and basin-evolution models of the sedimentary fill. The bioherms form 0.5-2.0 m diameter mound-shaped bodies and are concentrated within a single, oil shale-bound stratigraphic interval. Each bioherm is composed of up to 40% caddisfly cases along with stromatolites of millimeter-scale, micritic laminations. Petrographic analyses reveal these bioherms are composed of non-systematic associations of columnar and oncoidal microbialites, constructed around colonies of caddisfly cases. The cases are straight to curved, slightly tapered, and tube-shaped, with a progressively increasing length and width trend (7-21 mm by 1.5-2.5 mm). Despite these variations, the case architectures reveal similar construction materials; the particles used for cases are dominated by plant fragments, ostracod valves, carbonate rocks, and rare mica and feldspar grains. Allochems within the bioherms include ooids, ostracods, plant fragments, rare gastropods, feldspar grains bound in micritic matrices, and are consolidated by carbonate dominated cements. The combination of microbial-caddisfly association, plant fragment case particles, and ooids/oncoids are indicative of a shallow, littoral lake setting. Stratigraphic juxtaposition of nearshore bioherms and the bounding distal oil-shale facies suggests that the bioherms developed in an underfilled lake basin, resulting from an abrupt and short-lived lake desiccation event. Lake chemistry is believed to have been relatively alkaline, saline to hypersaline, and rich in Ca, Mg, and HCO3 ions. Through analyzing bioherm characteristics, caddisfly case architecture, carbonate microfacies, and stratigraphic variability, we infer larger-scale processes that controlled basin development during their formation.

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Garcia, Cédric. "Elaboration d'un dispositif médical contenant une association d'actifs naturels innovants dans le but de prévenir l'escarre." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM5501.

Повний текст джерела

Анотація:

Dans le cadre d’une hospitalisation, l’escarre est un souci majeur aussi bien pour le confort des patients que d’un point de vue économique. Le vieillissement de la population confronte de plus en plus le personnel soignant à la prévention et au traitement des escarres. La prophylaxie n’en est donc que plus essentielle dans les milieux hospitaliers. Force est de constater qu’il existe en la matière peu de produits spécialisés dont l’efficacité a été éprouvée. En partenariat avec le laboratoire RIVADIS, nous avons donc voulu élaborer un système galénique contenant une association d’actifs naturels innovants afin de prévenir l’escarre. Un état de l’art complet a été effectué sur la thématique des escarres afin d’en comprendre tous les facteurs de risques. Par la suite, une recherche approfondie a permis de sélectionner les plantes et molécules pouvant être utilisées comme actifs dans la prévention et/ou le traitement de cette pathologie. Notre attention s’est particulièrement attardée sur le pouvoir anti-inflammatoire, cicatrisant, antioxydant et anti-adhésion bactérienne de ces actifs. Les deux meilleurs actifs obtenus sont la pectine de pomme et l’extrait sec de Centella asiatica L., dont les résultats se sont avérés significatifs sur au moins trois propriétés recherchées. L’étude des effets combinés de ses deux actifs a même montré une synergie sur le pouvoir anti-adhésion bactérienne. Ils ont alors été incorporés sous forme galénique, de façon à rendre possible la réalisation d’un effleurage aussi facile que celui permis par les huiles déjà présentes sur le marché tout en autorisant l’incorporation d’actifs hydrophiles
In the case of a hospitalization, bedsores are a major issue regarding the comfort of the patient as well as economical reasons. Due to the aging population, the nurses are more and more confronted to prevention and treatment of bedsores. Thus, prevention is now considered as essential in hospitals. It must be noted that in matter of bedsores, there exist only a few specialized products which efficiency has been proved. Therefore, in association with RIVADIS Laboratory, we planed to work on a galenic formulation which contains a combination of innovative natural active. A complete compilation of specialized publications on this topic has been realized in order to fully understand all the risk factors. Then, thanks to an extensive research, we identified the plants and molecules that could be used as actives for the prevention and/or treatment of this pathology. We focused on their anti-inflammatory, healing, antioxidant and bacterial anti-adhesive properties. The two best actives thus obtained are apple pectin and dry Centella asiatica L. extract, they present significant results on at least three of the four wanted properties. Studying the combined effects of these two actives even showed a synergy on bacterial anti-adhesive property. They have then been incorporated in a galenic formulation that makes the massage as easy as the one allowed by already commercialised oils and enables the incorporation of hydrophilic actives

Стилі APA, Harvard, Vancouver, ISO та ін.

13

BUSCHI, EMANUELA. "Diversity of microbiomes associated with benthic invertebrates inhabiting Antarctic ecosystems." Doctoral thesis, Università Politecnica delle Marche, 2020. http://hdl.handle.net/11566/274555.

Повний текст джерела

Анотація:

Il numero sempre più alto di studi condotti sui microbiomi ha evidenziato l’importanza che queste associazioni rivestono nello sviluppo, nella salute e nella fitness degli organismi con cui i microbiomi vivono associati. In ambienti estremi come l’Antartide, i microbiomi sembrano avere un’importanza cruciale nel creare interazioni fondamentali per l’adattamento dei loro ospiti. Gli obiettivi di questa tesi sono: i) studiare la biodiversità dei microbiomi associati a diversi invertebrati marini antartici, ii) esplorarne l’origine, confrontando i microbiomi associati agli organismi con le comunità batteriche che abitano nei sedimenti circostanti, e iii) verificare se i fattori ambientali svolgano un ruolo attivo nel modellare la loro composizione tassonomica. I risultati hanno mostrato che, nonostante i microbiomi associati ai policheti antartici (Leitoscoloplos geminus, Aphelocaeta palmeri, Aglaophamus trissophyllus) possano variare in modo significativo tra gli individui, è possibile individuare dei core, sia a livello intraspecifico sia interspecifico, che contribuiscono significativamente all'intera comunità batterica associata. I taxa batterici associati ai policheti sono completamente diversi da quelli presenti nei sedimenti circostanti, suggerendo una potenziale trasmissione verticale o diverse capacità adattative dei microbiomi ai due diversi “habitat”. Molteplici fattori (i.e., non solo fattori ambientali ma anche quelli biologici come lo stato fisiologico e le abitudini di alimentazione) influenzano, a diversi gradi, la composizione tassonomica dei microbiomi associati ai policheti antartici. Nella stella marina antartica Odontaster validus la posizione geografica è il principale fattore che spiega le differenze trovate nella composizione tassonomica dei microbiomi, sebbene siano state riscontrate alcune somiglianze tra individui raccolti in luoghi diversi, suggerendo la presenza di altri fattori in grado di selezionare comunità batteriche simili. La presenza esclusiva di batteri specifici associati a stelle marine che vivono in determinate aree suggerisce una potenziale trasmissione orizzontale dei microbiomi, probabilmente acquisiti attraverso diverse abitudini alimentari che le stelle marine hanno sviluppato nelle suddette aree. Questa tesi di dottorato fornisce nuove informazioni sui microbiomi antartici, evidenziando una forte variabilità della loro composizione e complessità delle relazioni con gli ospiti esaminati, potenzialmente dovute, oltre ai fattori ambientali, anche alle caratteristiche biologiche degli ospiti.
Growing studies on host-associated microbiomes are highlighting the important role of microbes in the development, health and fitness of their hosts. This might be particularly true in remote and extreme environments, such as the Antarctic ecosystem, where the host and its microbiome could evolve together establishing peculiar and close interactions. This study aims: i) to investigate the biodiversity of microbiomes of different Antarctic invertebrates, ii) to explore the potential sources of the host-associated microorganisms by comparing them with microbial communities inhabiting the surrounding sediments, and iii) to verify the role of environmental setting in shaping their taxonomic composition. Results revealed that microbiomes of Antarctic polychaetes (Leitoscoloplos geminus, Aphelocaeta palmeri, Aglaophamus trissophyllus) showing significant variability among individuals, but that both intra-specific and inter-specific core microbiomes contribute for a significant fraction to the whole microbial assemblage. Bacteria associated with polychaetes were completely different from those in the surrounding sediments, suggesting a potential vertical transmission or the presence of different adaptative/selective conditions of the two “habitats”. Multiple factors (i.e., not only environmental factors but also biological ones such as physiological state and feeding habits) can influence to different extent the taxonomic composition of microbiomes associated with Antarctic polychaetes. In the Antarctic sea star Odontaster validus, the geographic location was identified as the main factor influencing the taxonomic composition of microbiomes, but this was not a general rule. In fact, high similarities were found among microbiomes of individuals collected in different locations, suggesting the presence of other drivers able to select similar microbial communities. The presence of exclusive bacterial families in sea-star microbiomes suggests a potential horizontal transmission of bacterial taxa, probably acquired through different feeding habits that the sea star might have developed in the different basins. This PhD thesis provided new information on Antarctic microbiomes, highlighting a strong variability of their composition and complexity of the relationships with the investigated hosts, potentially due to, besides environmental settings, also to hosts’ biological features.

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Drosinos, Eleftherios Haralambous. "Microbial associations of minced lamb and their ecophysiological attributes." Thesis, University of Bath, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358229.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Sydorchuk, L. I. "Microbial associations of the vaginal mucosa in trichomonal vulvovaginitis." Thesis, БДМУ, 2021. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/18684.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Stanbridge, L. H. "Microbial associations developing on modified atmosphere packaged beef steaks." Thesis, University of Bath, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239972.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Arkoudelos, John S. "Microbial associations of Greek meat, with special emphasis on fermented sausages." Thesis, University of Bath, 1992. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332314.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Boutebba, Abdelkader. "Propriétés du succinoglycane : transition conformationnelle et gélification en milieu aqueux." Université Joseph Fourier (Grenoble ; 1971-2015), 1998. http://www.theses.fr/1998GRE10136.

Повний текст джерела

Анотація:

Le succinoglycane est un polysaccharide charge d'origine bacterienne qui presente en solution aqueuse une transition conformationnelle ordre-desordre. La premiere partie de ce travail a porte sur l'etude de cette transition. Nous avons precise, a partir des proprietes polyelectrolytes, que la conformation ordonnee etait une simple helice. Nous avons montre le role particulier des substituants charges succinate sur la stabilite de cette helice. Quelle que soit la quantite de groupements succinate presents, l'enthalpie de transition par unite repetitive reste constante, ce qui montre que la contribution non polyelectrolyte a cette enthalpie est preponderante. Dans la deuxieme partie, nous avons cherche a comprendre l'origine et le mecanisme de la formation d'associations interchaines. Ces associations peuvent etre deja presentes dans la conformation native du polymere. Elles sont supprimees lors d'un premier passage au-dela de la temperature conformationnelle lorsque le parametre de recouvrement c est inferieur a 8. Pour des valeurs superieures, de nouvelles associations se forment de facon reversible lors de la transition desordre-ordre qui conduisent a la formation d'un gel faible et elastique. Une cinetique lente de stabilisation de ces associations est observee. Elles deviennent alors progressivement stables au-dela de tm mais semblent impliquer moins de 5% des segments des chaines. Dans la troisieme partie, les proprietes rheologiques des solutions ont ete etudiees. Nous avons retrouve, en absence d'associations, le comportement normal de solutions de polymeres et mis en evidence, dans certaines conditions, la formation d'associations intermoleculaires. L'influence de la temperature a ete reliee a la rigidite des chaines et a l'aptitude de ce polymere a former des associations interchaines.

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Moon, Jinyoung. "Selective accrual and dynamics of proteinaceous compounds during pedogenesis: testing source and sink selection hypotheses." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/77030.

Повний текст джерела

Анотація:

The emerging evidence of preferential accumulation and long residence time of proteinaceous compounds in soil are counter to the traditional view that their structure is readily broken down through microbial activity. The shift in thinking of their residence time is, however, heavily influenced by physical and chemical protections in soil, representing an important change for understanding global biogeochemical carbon and nitrogen cycling. We investigated the accumulation patterns of proteinogenic amino acids for a long term (thousands of years) related to their sources and sinks. We found clear patterns of change in the amino acids in a 4000 year-chronosequence adjacent to Lake Michigan, USA (Michigan chronosequence) and they were tightly related to the shifts in their biological sources, namely aboveground vegetative community (r2=0.66, p<0.0001) and belowground microbial community (r2=0.71, p<0.0001). Results also showed great variations of approximately 49% between seasons (summer and winter). Moreover, seasonal dynamic patterns (22% variations) of the amino acids in soil mineral associated fraction were rather counter to the conceptual view that it represents a slow soil organic pool with long residence times. The amino acids enriched in the mineral associated fraction, (e.g., positively charged, aromatic, and sulfur containing amino acids), tended to preferentially accumulate in whole soil pool during the 4000 years of ecosystem development. Their interaction with soil minerals, therefore, may play a critical role in the long-term sink and selective accumulation of proteinaceous compounds with some degree of the displacement. This was further confirmed by another chronosequence system near Haast River, New Zealand, which is geologically separated and climatically- and ecologically- different from the Michigan chronosequence. Common trends between two chronosequences suggested that either polar interactions or redox reactions may be relatively more important in the mineral interaction of amino acids than non-polar interactions. The consistency of results at two disparate locations in the southern and northern hemispheres is strong evidence that the processes of pedogenesis and ecosystem development are parsimonious and predictable. Our research demonstrated fundamental understanding of behavior of proteinaceous compounds at the molecular species level, and further provided their partitioning mechanisms associated with soil components.
Ph. D.

Стилі APA, Harvard, Vancouver, ISO та ін.

20

McDowall, Alex. "The toxicity of o-cresol and 2,4-dimethylphenol on anaerobic microbial associations." Thesis, University of Strathclyde, 2014. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23202.

Повний текст джерела

Анотація:

The study of anaerobic bacterial growth associations plays an important role in the analysis of the toxicity and effect of pollutants. These associations can be found in the environment, for example in groundwater or wastewater treatment plants or even in the gut of animals. The aims of this study were to compare the toxicity exhibited on anaerobic growth associations by two similar alkylphenolic compounds, o-cresol and 2,4-dimethylphenol (DMP), individually and combined, and examine the specific effect these compounds had on individual bacterial groups within the consortium. Through the use of anaerobic batch cultures, the inhibitory concentrations and effects of o-cresol and 2,4-dimethylphenol on anaerobic processes were analysed. Concentrations of o-cresol = 1.85mM were shown to have an inhibitory effect on sulphate reduction, acetogenesis and methanogenesis. At concentrations = 7.4mM complete inhibition of sulphate reduction was noted and the acetogenic and metha nogenic processes were greatly reduced, concentrations = 9.3mM appear to cause complete inhibition of methane production. 2,4-dimethylphenol inhibited bacterial groups at concentrations =0.41mM; complete inhibition of sulphate production was observed at concentrations of DMP =3.28mM. Although methane production was significantly reduced at the highest concentration (4.1mM) complete inhibition was not observed. It was found that DMP was more toxic to all the bacteria and archaea within the consortium than o-cresol. Use of continuous flow systems allowed for the separation of the microbial groups within the consortium allowing for the analysis of the direct effect of o-cresol and 2,4- Dimethylphenol. Analysis of the results indicated that the compounds inhibited all the microbial groups, although with varying x degrees of success. It was observed that acetoclastic methanogenic bacteria are more resilient to the toxic effect of the compounds than h methanogens and sulphate reducing bacteria. The combined toxicity of these compounds was analysed utilising batch cultures. The combined toxic effect on the growth consortium was observed after addition of both of these compounds to batch cultures. The results showed that, when combined, these compounds exhibited a toxic effect on the consortium, which was synergistic in nature. This study has highlighted the toxic effects of o-cresol and DMP on anaerobic consortia and the importance of the synotrophic relationships between the different bacterial and archaeal groups. It is important that work in this field is carried on to develop a better understanding of the implications of toxic chemical spills and their impact on the groundwater environment.

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Mazur, O. O. "The role of microbial associations in chronic purulent rhinosinusitisin patients for type 1 diabetes mellitus." Thesis, БДМУ, 2022. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/19806.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Omer, Zahra Saad. "Bacterial-plant associations with special focus on pink-pigmented facultative mehtylotrophic bacteria (PPFMs) /." Uppsala : Dept. of Plant Pathology and Biocontrol Unit, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/a456-ab.html.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Martin, Makenna May. "Microbial Associations of Four Species of Algal Symbiont-Bearing Foraminifera from the Florida Reef Tract, USA." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7337.

Повний текст джерела

Анотація:

Marine microbiome research is a rapidly expanding field of study, as scientists investigate the functions of microbial associations in eukaryotic organisms. Foraminifera are among the most abundant shelled organisms in the oceans, yet little is known of their associated microbiomes. This study investigated microbes associated with four species of Foraminifera that host three kinds of algal endosymbionts. The Order Miliolida, Family Soritidae, was represented by three species: Archaias angulatus and Cyclorbiculina compressa, which both host chlorophyte symbionts, and Sorites orbiculus, which hosts dinoflagellate symbionts. The fourth species, Amphistegina gibbosa, belongs to the Order Rotaliida and hosts diatom endosymbionts. Bacterial DNA extraction was attempted from 5−8 specimens per species followed by amplification and amplicon sequencing of the V4 variable region of the 16S rRNA gene. Three Ar. angulatus specimens shared 177 Operational Taxonomic Units (OTUs), and six C. compressa specimens shared 58 OTUs, of which 31 OTUs were found in all specimens of both species. Four S. orbiculus specimens shared 717 OTUs dominated by Proteobacteria, notably Amoebophilaceae. The three soritid species shared 26 OTUs, predominantly representing the bacterial families Rhodobacteraceae and Flavobacteriaceae. Since S. orbiculus shared 84% of the OTUs shared by Ar. angulatus and C. compressa, which host similar endosymbionts, phylogenetic relatedness of host taxa clearly had more influence on core microbiomes than the algal-symbiont taxon. The microbiomes of three normal-appearing and five partly-bleached specimens of Am. gibbosa varied widely, sharing only six OTUs, four of which represented Proteobacteria. All four species shared only four OTUs, three of which may have been contaminants. As the first known microbiome study to include western Atlantic/Caribbean benthic foraminifers that host algal endosymbionts, the results for Am. gibbosa revealed quite similar results to a recent study of the microbiome of Am. lobifera, a closely related Indo-Pacific taxon.

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Van, Zwieten Lukas. "Enhanced biodegradation of phenoxyacetate and triazine herbicides by plant-microbial rhizoplane associations and adapted soil microorganisms." Thesis, The University of Sydney, 1995. https://hdl.handle.net/2123/26900.

Повний текст джерела

Анотація:

Strategies for the enhanced biological degradation of pesticides were examined in this research project. In one approach, the concept of the plant—microbial rhizosphere association was investigated as a laboratory model using the herbicide 2,4-D as a test compound. In another, an enhanced degradation of the recalcitrant herbicide atrazine was shown. Here, two microbial populations each capable of rapid atrazine metabolism were studied. The metabolism of 2,4-D by bacteria associated with the root system of wheat and canola seedlings was demonstrated in this study using a hydroponic system as well as a solid medium of sand and gravel. Significant and rapid 2,4-D metabolism (near 100% within 24h) was found in all hydroponic systems where the 2,4-D degrading microorganisms, Acinetobacter baumannii pJP4 transconjugant, Alcaligenes eutrophus and Azospirillum brasilense pIP4 transconjugant were associated with the roots. The metabolism of 2,4-D by Azospirillum brasilense pJP4 transconjugant associated with wheat was less rapid than associations with the other 2,4-D degrading bacteria. There was little difference in the rates of degradation between the hydroponic system and the sand/gravel mixture. The colonisation of the roots of seedlings by microbes was studied by both fluorescence and laser scanning confocal microscopy. Colonisation was often prolific without favoured areas of attachment on the root. A pre-treatment of seedlings with a synthetic auxin which formed para-nodular structures had little effect on the nature of colonisation. Counts of colony forming units, however, established that there was an increase of an order in magnitude of cells per root system when the plants were pretreated with this synthetic auxin. An average of 5.5 x 106 viable cells of 2,4-D degrading Acinetobacter baumannii were counted on para-modulated wheat root systems. It was demonstrated that the colonisation of the rhizosphere by suitable microbes could protect canola seedlings against phytotoxic effects of the applied herbicide. Whether this bio-safening effect will be seen in solid media or in field situations with these nonleguminous plants was not investigated. Significant rates of atrazine degradation either in the laboratory or in the field have rarely been reported. Attempts were therefore made to obtain microbes capable of such metabolism. These attempts had the ultimate goal of providing microbes for application in the model plant microbial rhizosphere association. Two microbial cultures, each capable of rapid atrazine metabolism, were obtained and studies of the metabolic processes were conducted. Rhodococcus sp. NI86/21 metabolised atrazine within l44h to two N—dealkylated products, desisopropylatrazine and desethylatrazine. Mineralisation of the ethyl-14C labelled sidechain to 14CO; was demonstrated, accounting for 25% of the total applied label in the broth culture. Desisopropylatrazine was shown to be the major metabolite. Desethylatrazine was shown as a terminal metabolite in the degradation of atrazine by Rhodococcus sp. N186/21, accumulating in the broth. In other studies using it as the substrate, no firrther metabolism was found. Desisopropylatrazine was also indicated to have been a terminal metabolite as it too accumulated in the broth. The metabolism of prometryn, a thio-ester (non-chlorinated) s-triazine was also investigated in these studies. Although Rhodococcus Sp. N186/21 did not rapidly degrade prometryn under similar conditions to those used with the atrazine assays, a mono-N-dealkylated metabolite was identified by mass-spectrometry. Possibly, prometryn was toxic to the Rhodococcus at the concentration used (lOug mL'l), as only minimal growth of the bacteria in the broth was observed by increased absorbance. Such a toxic effect was likely to have inhibited the N-dealkylation metabolism of the prometryn. In another approach, soil from a pesticide sullage site on a farm in northern NSW was assayed for its atrazine metabolising ability. Although there was no initial activity, after 30 months of perfirsion of the soil with a concentrated solution of the herbicide, it had acquired the ability to rapidly mineralise atrazine. A rapid conversion of the three carbons in the s—triazine ring to C02 was demonstrated using radiolabelled atrazine. Also, the labelled carbon in the ethyl sidechain of atrazine was rapidly metabolised to CO2. The sidechain 14C label was mineralised to 14C02 at a slower rate than the carbons in the ring. It was demonstrated that there was a likelihood of the sidechain carbon being incorporated into an unextractable intermediate metabolite, which was subsequently also less susceptible to attack by the microorganisms. There were no significant metabolites of atrazine accumulated in the broth. The likely presence of hydroxyatrazine was noted in the assay using uniformly ring—labelled [14C] atrazine. Hydroxyatrazine was also identified in the assay with ethyl-sidechain labelled [14C] atrazine, however, the amount detected was less. The presence of atrazine at 25pg mL-l inhibited nitrification reactions in the soil, however, at a saturating concentration of SOug mL-l there was some ammonia oxidation noted. Attempts to isolate single bacterial colonies capable of the metabolism of atrazine were unsuccessful. Although there was insufficient time to utilise these microbial cultures in the plant microbial rhizosphere associations, studies on the metabolism of atrazine have sufficiently characterised the nature of biodegradation to suggest that plant-microbial associations can be confidently tested in fiiture experiments.

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Rodrigues, Richard Rosario. "Investigating Structure and Function of Rhizosphere Associated Microbial Communities in Natural and Managed Plant Systems." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/79658.

Повний текст джерела

Анотація:

Many plants, especially grasses, have Nitrogen (N) as their growth-limiting nutrient. Large amounts of N fertilizer (>100 kg N ha-1) are used in managed systems to maximize crop productivity. However, the plant captures less than 50% of the (~12 million tons per year, U.S.) applied N-fertilizer. The remaining mobile N lost through leaching and denitrification accumulates in waterways and the atmosphere, respectively. Losses of fertilizers create environmental and economic concerns globally and create conditions that support the invasion of exotic plants in the natural landscapes. There is thus a need to come up with biological solutions to better manage nitrogen for plant growth and ecosystem sustainability. Microbial communities in the rhizosphere are known to potentially have beneficial effects on plant growth. Diazotrophs, for example, are bacteria that can convert the atmospheric nitrogen to ammonia, a process called 'nitrogen fixation.' Utilizing the natural process of associative nitrogen fixation to support most of the plant's N needs would substantially reduce fertilizer use and thus reduce production and environmental costs. The goal of this dissertation was to determine the structure and function of root-zone microbial communities for increasing productivity of native plants. Towards this end, we study the root-zone bacterial and fungal communities of native and exotic invasive plants. This study identifies that shifts in rhizosphere microbial communities are associated with invasion and highlights the importance of rhizosphere associated structure and function of microbes. A study of root-zone associated microbes in switchgrass (Panicum virgatum L.) - a U.S. native, warm-season, perennial, bioenergy crop indicates that high biomass yield and taller growth are associated with increased plant N-demand and supportive of bacteria with greater rates of N2-fixation in the rhizosphere. Another crucial outcome of the thesis is a better description of the core and cultivar-specific taxa that comprise the switchgrass root-zone associated microbiome. The work in this dissertation has brought us closer to designing N supply strategies by utilizing the natural microbial communities to balance the N-cycle in agroecosystems and support a sustainable environment.
Ph. D.

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Hall, Kimberlee K., Brian G. Evanshen, Kurt J. Maier, and Phillip R. Scheuerman. "Application of Multivariate Statistical Analyses to Microbial Water Quality Parameters in Four Geographically Similar Creeks in Northeast Tennessee to Identify Patterns Associating Land Use to Fecal Pollution Sources." Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etsu-works/2947.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Poggenburg, Christine [Verfasser]. "Microbially-mediated transformation and mobilization of Fe-organic associations in the soil / Christine Poggenburg." Hannover : Technische Informationsbibliothek (TIB), 2018. http://d-nb.info/1163206032/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Драпой, Дарина Ігорівна. "Одержання водню з целюлозовмісної сировини". Doctoral thesis, Київ, 2021. https://ela.kpi.ua/handle/123456789/43553.

Повний текст джерела

Анотація:

Дисертація присвячена науково-технічним основам технології ферментації сільськогосподарських відходів з отриманням водню. В дисертаційній роботі було виділено ефективну асоціацію мікроорганізмів-деструкторів целюлози та продуцентів водню. За основу взято природну асоціацію мікроорганізмів з ґрунту, що зменшує вміст в асоціації консументів водню – сульфатредукуючих мікроорганізмів, в порівнянні з природними асоціаціями з мулу та проточних водойм. В роботі експериментально визначено, що для знешкодження метаноутворюючих мікроорганізмів необхідно проводити температурну обробку інокуляту при t = 90ºС протягом 1 години. За даної обробки мікроорганізми родів Clostridium та Bacillus утворюють спори, що проростають вже за 2 дні за сприятливих умов. Визначено, що додаткове збагачення асоціації мікроорганізмами родів Clostridiuт та Bacillus призводить до збільшення виходу водню в порівнянні з вихідною асоціацією. При чому вміст водню в біогазі залежить від кількості та співвідношення мікроорганізмів, що додаються. Встановлено, що збагачення асоціації культурами мікроорганізмів родів Clostridium та Bacillus у співвідношенні 1:2,5 дає можливість збільшити вихід водню в 2,3 рази. Визначено раціональний метод попередньої обробки сировини (3 год, 20% NaOH) що дозволяє підвищити вихід водню у 3 рази. Луг ефективно видаляє лігнін з біомаси, покращує доступність целюлози та збільшує площу адсорбція субстрату для мікроорганізмів. В дисертаційній роботі наведено математичний опис продукування біогазу залежно від значення рН та концентрації субстрату, що дозволяє моделювати довільний характер процесу і визначати оптимальні умови продукування водню в залежності від змінних параметрів процесу. Визначено основні технологічні параметри процесу ферментації целюлозовмісної сировини з продукуванням водню: температура процесу – 35ºC, рН - 7 – 7,5, концентрація сировини - 50 ± 5 г/дм3, співвідношення інокуляту до субстрату 1:4, постійне відведення водню з зони ферментації, що дозволяє одержати біогаз з вмістом водню 87,5±4,2%.

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Abdul-Halim, K. K. "Preliminary elucidation of the methanogenic fermentations of veratric and syringic acids by interacting microbial associations isolated from anoxic freshwater sediment." Thesis, University of Stirling, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381514.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Lam, Kin-San. "Biodegradation of xanthate by microbes isolated from a tailings lagoon and a potential role for biofilm and plant/microbe associations /." View thesis, 1999. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030828.084802/index.html.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Partula, Valentin. "A nutritional epidemiology study of human gut microbiota - Associations with the systemic metabolism and usual diet of the host and relationships between dietary fibers and the host’s health." Thesis, Université de Paris (2019-....), 2019. http://www.theses.fr/2019UNIP7119.

Повний текст джерела

Анотація:

Il est désormais admis que le microbiote intestinal joue un rôle prépondérant dans la santé de son hôte humain. Le co-métabolisme hôte-microbiote produit un très grand nombre de biomolécules intégrées au sein d’axes métaboliques complexes. De ce fait, le microbiote intestinal est considéré comme un organe endocrine à part entière. Bien que de nombreuses études se soient attachées à la caractérisation fonctionnelle spécifique de certaines molécules, les études envisageant plus globalement les relations métaboliques entre l’hôte et son microbiote intestinal restent rares. Parmi les nombreux facteurs influençant la composition et l’activité métabolique du microbiote intestinal, l’alimentation joue un rôle prépondérant. Toutefois, les relations entre l’alimentation usuelle et le microbiote intestinal n’ont pas été complètement élucidées. La compréhension des facteurs modulant le microbiote intestinal est un enjeu majeur des recherches actuelles, car des liens entre le microbiote intestinal et de nombreuses pathologies (troubles gastro-intestinaux, cardio-métaboliques, neuropsychiatriques, etc.) ont été suggérés. Dans ce contexte, nous avons utilisé une approche épidémiologique pour caractériser les associations entre la composition du microbiote intestinal d’une part et le métabolisme systémique et l’alimentation usuelle de l’hôte d’autre part, au sein de la population Milieu Intérieur (N=1 000). Enfin, dans la cohorte prospective NutriNet-Santé (N≈160 000), nous avons analysé les associations entre la consommation de fibres d’une part et le risque de maladies chroniques et le microbiote intestinal d’autre part.Nos résultats décrivent des associations spécifiques entre les caractéristiques du microbiote intestinal et certaines composantes du métabolisme de l’hôte, et suggèrent un rôle important de l’axe intestin-rein. De plus, des associations inverses entre la diversité du microbiote intestinal et la consommation d’aliments caractéristiques du régime occidental ont été détectées. Enfin, nos travaux confirment que la consommation de fibres est associée à une réduction du risque de maladies chroniques, dans un contexte où un nombre croissant d’études suggère une implication du microbiote intestinal dans de tels effets
It is now admitted that the gut microbiota plays a key role in the health status of its human host. It is indeed fully recognized as an endocrine organ producing biologically active molecules which are integrated within human metabolism. However, comprehensive studies characterizing host-gut microbial metabolic relationships remain scarce. Numerous factors have been shown to exert a modulatory impact on the gut microbiota. Notably, diet is supposed to be a major driver, but the relationships between usual diet and the gut microbiota are not fully elucidated yet. Furthermore, many studies have suggested the implication of the gut microbiota in a wide range of disease states, such as gastrointestinal, cardio-metabolic, neuropsychiatric, etc. disorders. Thus, understanding the factors influencing the gut microbiota constitutes an active area of research. In this context, we adopted an epidemiological approach to investigate one of the largest population-based samples so far (Milieu Intérieur population, N=1,000). We notably assessed the associations between gut microbiota composition on one hand and the systemic metabolism and the usual diet of the host on the other. Finally, in the NutriNet-Santé cohort (N≈160,000), we investigated the associations between the intake of dietary fibers and the risk of a variety of chronic diseases, and described how dietary fibers are associated with the gut microbiota.Overall, our results suggest that gut bacterial features are specifically associated with certain components of the systemic metabolism of the host, and we hypothesize a substantial role of the gut-kidney axis. Besides, negative associations between food items for which a limited consumption is generally recommended (i.e. processed foods) and gut microbial features were detected. Additionally, we confirm robust inverse associations between the consumption of dietary fibers and several major chronic diseases. Mounting evidence suggests that such effects could be mediated by the gut microbiota

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Lam, Kin-San. "Biodegradation of xanthate by microbes isolated from a tailings lagoon and a potential role for biofilm and plant/microbe associations." Thesis, View thesis, 1999. http://handle.uws.edu.au:8081/1959.7/441.

Повний текст джерела

Анотація:

Xanthates, key compounds used in the mining industry for the separation of metals from ores, may have a significant impact on the ecosystems once discarded into the tailings. The aims of this study were to : characterize chemical and microbiological conditions in a tailings lagoon (Brown Creek gold mine); examine the feasability of using indigenous bacteria to degrade xanthate under laboratory conditions; and, optimize the biodegradation process by employing biofilm technology and plant-microbe associations. To achieve these, a simple but accurate HPLC method was developed. The chemical and biological constitution of the tailings lagoon was monitored over a 2 year period from March 1995 to February 1997. Xanthate degradative performance was improved by Phragmites australis and its root associated bacterial community. Cumulative amounts of xanthate degraded by this plant-microbe association were significantly higher than any other treatment, specifically glass-attached and free-living bacterial populations. An increased bacterial number in the extensively developed root, the presence of extracellular layer as revealed from scanning electron microscope and significance of plant removal via uptake were thought to be the possible explanations for the enhanced biodegradation activity observed. In view of the above, use of glass-attached bacteria and plant-microbe associations might provide a feasible solution to degrade xanthate in the tailings lagoon. The results obtained from this study suggest that the plant-microbe associations could provide a cost effective method to degrade/remove xanthate from the tailings lagoon runoff. This approach offers several ecological advantages. Firstly, it offers the advantage of a solar-powered treatment system that is aesthetically pleasing. Secondly, bioremediation can be done on site, thereby eliminating waste transportation costs. Finally, it has the added attraction of a higher potential for public acceptance

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Conner, Lafe G. "Environmental and Adaptive Buffers that Mediate the Response of Subalpine Ecosystems to Environmental Change." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5913.

Повний текст джерела

Анотація:

This document reports the results of 4 studies of subalpine ecosystem ecology, describing ways that spatial heterogeneity in soils and plant communities mediate ecosystem responses to environmental change. Ecosystem responses to environmental change are also mediated by regional climate patterns and interannual variability in weather. In the first chapter we report the results of an experiment to test for the mediating effects of associational resistance in a forest community that experienced wide-spread beetle kill. We found that Engelmann spruce were more likely to survive a beetle outbreak when growing in low densities (host dilution) and not through other types of associational resistance that relate to higher tree-species richness or greater phylogenetic diversity of the forest community. In the second chapter we report the effects of early snowmelt on soil moisture in subalpine meadow and aspen communities. We found that soil organic matter, soil texture, and forest cover mediated the effects of early snowmelt and were more important drivers of growing-season soil moisture than was snow-free date. In the third chapter we report the effect of early snowmelt on growth and seed production of early-season and midsummer herbaceous species. We found that the primary effect that snowmelt timing had on plant growth was through its effect on species distribution. Changes in the timing of snowmelt had limited effect on the growth, flowering, and seed count of species after they were established. In the final chapter, we report the effect of early snowmelt on soil respiration, microbial biomass, dissolved organic carbon and soil organic carbon. We found that early snowmelt resulted in warmer soil temperatures compared to neighboring snow-cover plots, and that microbial biomass and soil respiration showed no signs of a snowmelt legacy effect during the growing season. Soil organic carbon in rapid and slow-turnover pools was affected more by plant community than by snowmelt timing, and the primary drivers of soil respiration during the snow-free period were first soil organic matter and second soil temperature. Taken together, this dissertation reports our findings that subalpine ecosystems are resilient to environmental change in part because organisms in these systems are adapted to environmental conditions that are highly variable between sites, seasons, and years.

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Santos, Pedro Ivo de Almeida. "Remoção de DQO e de nitrogênio, e estudo dos consórcios microbianos em sistema com três reatores sobrepostos, em série, alimentado com esgoto sanitário." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-25052005-003933/.

Повний текст джерела

Анотація:

Esta pesquisa enfoca a avaliação do desempenho de nova configuração de unidade para tratamento biológico de esgoto sanitário por processo combinado, visando à remoção de nutrientes, especialmente nitrogênio. O sistema construído em escala piloto tem volume útil igual a 71,48 litros. Nesta nova configuração de reatores para tratamento terciário de esgoto sanitário, utilizaram-se três reatores sobrepostos, sendo: um reator UASB - Upflow Anaerobic Sludge Blanket; um reator de leito móvel e filme fixo aeróbio (com aplicação de oxigênio puro); e, um reator de leito móvel e filme fixo com ambiente anóxico. O material suporte utilizado nos reatores de leito móvel e filme fixo constituiu alternativa inédita no tratamento de efluentes líquidos. Foram utilizadas cavilhas ranhuradas de madeira, de dimensões aproximadas de 8,0 mm de diâmetro por 8,0 mm de comprimento. O desempenho geral do sistema quanto à remoção de matéria carbonácea e compostos nitrogenados, e as associações microbianas formadas nos três reatores são objetos principais de estudo deste trabalho. Foram obtidos resultados de remoção de DQO e de nitrogênio bastante satisfatórios, sobretudo quando o tempo de detenção hidráulica total esteve próximo a 20 horas, incluindo o compartimento de decantação (94,6 % para DQO; e 96,7 % para N-NTK, com formação de nitrato em concentrações inferiores a 10,0 mgN-NO3-/l). O TDH estudado variou entre 5 e 24 horas para os sistema completo. O estudo dos consórcios de microrganismos forneceu excelentes resultados quanto à quantidade, diversidade, e atividade das populações desenvolvidas nos diferentes ambientes, confirmando o bom desempenho do sistema e o fornecimento de ambiente adequado para o desenvolvimento das diferentes populações nos três reatores. A idealização desta configuração tem como finalidade realização de tratamento de esgoto sanitário até nível terciário em planta compacta, podendo ser utilizada por pequenas e grandes comunidades, devido à possibilidade de se construir diversos módulos do sistema proposto.
This research is focused on the performance evaluation of a new system configuration of combined biological reactors, treating domestic wastewater till tertiary level. The pilot scale proposed system had a total useful volume of 71,48 liters. This new configuration involves three types of superposed reactors: an Upflow Anaerobic Sludge Blanket reactor; an aerobic fixed film mobile bed reactor (fed with pure oxygen); and a fixed film mobile bed reactor at anoxic environment. The support material used inside the fixed film mobile bed reactors was wood made grooved dowels. The main purposes of this work are to evaluate the systems general performance regarding COD and nitrogen removal, and the microbial associations inside the reactors. It reached quite satisfactory results regarding COD and nitrogen removal when the total hydraulic retention time (HRT) was around 20 hours, including the clarification zone volume (94,6 % for the COD; and 96,7 % for the TKN-N, whit nitrate formation below 10,0 mgN-NO3-/l). HRTs from 5 to 20 hours were studied. The microbial associations were present in large number, with a great diversity and high specific activities at the different environments, confirming the good results obtained and the suitable environment provided for the growth of the different populations inside the three reactors. The idealization of this treatment system has the goal to treat domestic wastewater from small to large communities till tertiary level, in compact treatment plants, due to the possibility of constructing several modules of the system.

Стилі APA, Harvard, Vancouver, ISO та ін.

35

"Microbial Programming of the Neonatal Pig." Thesis, 2013. http://hdl.handle.net/10388/ETD-2013-07-1175.

Повний текст джерела

Анотація:

Microbial succession, composition and ecological distribution within the gastro-intestinal tract are critical areas of study since commensal bacteria have been shown to affect animal health and development. A series of experiments were conducted to determine whether altered microbial succession in neonatal animals would modulate the development and health of pigs later in life. An initial experiment in conventional pigs was conducted to establish the early postnatal microbial succession profile and to identify early colonizing bacterial species. Culture-independent analysis of digesta and mucosal microbiota showed distinct variation between the proximal and distal gastro-intestinal tract (GIT) indicating that fecal or distal gut profiles cannot be used to predict succession in the upper GIT. Temporally, Clostridium spp. were found to be most prevalent in the GIT microbiota of the neonatal pig up to 0.5 d of age, accompanied by a high abundance of Escherichia and Shigella spp. These genera were transiently displaced by Streptococcus spp. followed by a preponderance of Lactobacillus spp. between 3 and 20 d of age. Subsequently, a “snatch-farrow” model was employed to modulate early postnatal microbial succession and investigate the effects on postweaning microbial composition. Pigs were collected into sterile towels directly from the vaginal canal and transferred to a sterile isolator environment for the first 4 days. Pigs were either inoculated with sow feces or not at 1 d of age resulting in significant differences in fecal microbial profile at 4 days of age, prior to removal from isolators. Analysis using terminal restriction fragment length polymorphisms (TRFLP) of intestinal microbiota at 28 d of age did not show significant clustering or variation in diversity indices for either group during the 4-d postnatal isolator phase. However, enumeration of selected taxa using quantitative PCR did indicate significant treatment differences in postweaning microbiota. Despite these results, this approach was rejected for further use as the protocol provided only moderate control of early postnatal colonization and variation and unpredictability of the timing of natural farrowing contributed to significant litter effects. Finally, a gnotobiotic monoassociation model was used investigate the effects of modulating early postnatal microbial succession on postweaning physiology, microbial composition and mucosal gene expression. Twenty-four cesarean-section derived piglets were monoassociated for the first 4 days of life with either L. mucosae (L), S. infantarius (S), C. perfringens (C) or E. coli (E). Pigs from treatments E and L animals showed the highest growth rate during the conventional rearing period (7-28 d of age). Monoassociation with different bacterial species during the first 4 d of life resulted in significant changes in postweaning microbial composition in small intestine and colon as assessed by quantitative PCR, although TRFLP did not identify unique clustering by treatment or variation in diversity. L. mucosae was the only inoculant species with significant variation, with a reduction in the colonic mucosa at 28 days of age. Monoassociation with L. mucosae was also associated with increased nutrition related gene expression in small intestine. Pigs monoassociated with E. coli had low expression of microbial sensing (TLR2 and 4), NFkappaB complex genes and mucins at 28 d of age. This study clearly showed that controlled early microbial succession in neonatal pigs altered post-weaning commensal microbiota composition, postweaning physiology and host gene expression in small and large intestine. The findings suggest the importance of peri-natal management and feeding strategies in promoting postweaning health and performance.

Стилі APA, Harvard, Vancouver, ISO та ін.

36

Li, Maohao, and 李茂豪. "Occurrence of microbial antibiotic resistance in the water environment in association with swine wastewater." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/12133697984424266874.

Повний текст джерела

Анотація:

碩士
東吳大學
微生物學系
101
Emerging pollutants are consist of organic pollutants, industrial chemicals, pharmaceuticals and personal care products (PPCPs) and endocrine interfering substances. Traditional wastewater treatment process has low efficiency of removing emerging contaminants , such that the pollutants can easily enter the aquatic environment, and may result in the impact of environmental ecosystem . In Taiwan, antibiotics is the most widely use of PPCPs, among which the antibiotics for animals is widespread. In order to understand the impact of waste water discharges to the environment from pigs farms in Taiwan, levels of tetracycline and sulfonamide antibiotics in wastewater, and antibiotic resistant microorganisms in the environment were determined, and the assess of its impact on the environment system was addressed. Samples including swine wastewater, upstream and downstream of the river surface water relative to the site where wastewater discharged, soils of the riverbank, sludge and water of adjacent well were collected and analyzed. The results indicated that higher percentage of tetracycline and sulfonamide resistant microorganisms present in the wastewater. The number and percentage of the antibiotic resistant bacteria in the downstream river water was significantly higher than there of upstream river water, These resistant microorganisms exhibited higher antibiotic resistance gene loadings and multiple drug resistance. The denaturing gradient gel electrophoresis (DGGE) was used to analyze the microflora 16S rDNA and tetracycline resistance gene tetW diversity, and the results indicated that although microflora of each sample with high diversity, tetW gene can be classified into only 2 groups of very high similarity in these sequences, suggesting that horizontal gene transfer the resistance gene is likely to occur from microorganisms in the wastewater of pig farms to the microorganisms in river water. Isolates of sulfonamide resistant microorganisms from each sampling site also showed substantial phylogenetic divergence with high nucleotide identity of resistance genes. The pig farm wastewater and downstream river water detected a higher number of class 1 integrons, and three types of resistance genes embedded. In summary, the results show antibiotic resistant microorganisms in the swine wastewater discharged into the water environment can increase the number of antibiotic resistant microorganisms in the environment, expand the size and variety of gene pool of the antibiotic resistant genes in the overall environment. It may have an effect on the environmental ecosystem due to bioaccumulation or transfer to potential pathogens, and contribute to a potential risk of harm to human health and ecological.

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Silva, Cláudio José Nunes. "Association between an oral commensal (Fusobacterium nucleatum) and colorectal carcinogenesis: to what extent do we tolerate our microbial self?" Master's thesis, 2016. https://repositorio-aberto.up.pt/handle/10216/89874.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Silva, Cláudio José Nunes. "Association between an oral commensal (Fusobacterium nucleatum) and colorectal carcinogenesis: to what extent do we tolerate our microbial self?" Dissertação, 2016. https://repositorio-aberto.up.pt/handle/10216/89874.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

39

"Association of chickpea with soil fungi: a comparison of cultivars." Thesis, 2014. http://hdl.handle.net/10388/ETD-2014-11-1848.

Повний текст джерела

Анотація:

Certain crop plants are susceptible to pathogens or unable to develop efficient microbial symbioses. These crops adversely impact soil biological quality with consequences on plant health and productivity of cropping systems. Chickpea is a rotational pulse crop with two types: kabuli and desi, and several cultivars. Cultivation of chickpea has inconsistent effects on soil microbial communities and subsequent wheat crops. I conducted field studies and used high throughput molecular analyses to explore the variations among chickpeas to identify cultivars developing fungal communities that are conducive to plant health and productivity. I also carried out greenhouse studies and used biochemical analyses to investigate the response of chickpea cultivars to arbuscular mycorrhizal (AM) fungi and non-AM fungal endophytes and identify the influence of root and root metabolites on the endophytic and pathogenic fungi. Cultivars and types of chickpeas and environmental conditions promoted different fungal communities in the root endosphere. Funneliformis and Claroideoglomus were the dominant AM fungal genera and Fusarium and Alternaria were the dominant non-AM fungal genera in the roots of chickpea. The roots of cultivars CDC Corrine, CDC Cory and CDC Anna hosted the most diverse fungal communities in contrast to CDC Alma and CDC Xena roots which hosted the least diverse communities. Plant response to AM and non-AM fungal endophytes varied with genotype and type of chickpea. The root symbiosis effectively promoted plant growth in CDC Cory, CDC Anna and CDC Frontier and stimulated nitrogen fixation in CDC Corrine. Cultivars of chickpea responded differently to dual inoculation of the AM and non-AM fungal endophytes. Co-inoculation with AM and non-AM fungal endophytes had additive effects on CDC Corrine, CDC Anna and CDC Cory but non-AM fungal endophytes reduced the positive effect of AM fungi in Amit and CDC Vanguard. Desi chickpea appeared to form more efficient symbioses with soil fungal resources than kabuli chickpea. Protein(s) up-regulated in the mycorrhizal roots of the desi chickpea CDC Anna suppressed the growth of the fungal endophytes Trichoderma harzianum and Geomyces vinaceus and of the pathogens Fusarium oxysporum and Rhizoctonia sp. The formation of AM symbiosis decreased the production of root bioactive metabolites soluble in 25% methanol. Some of the root metabolites stimulated the growth of Trichoderma harzianum and Geomyces vinaceus, and a few inhibited Rhizoctonia sp. and Fusarium oxysporum. A few metabolites with contrasting effects on the different fungal species were detected. The non-protein phytochemicals had selective effects on the endophytes and pathogens whereas the antifungal proteins of mycorrhizal roots were non-selective. Overall the study reveals a "genotype effect" of chickpea on the soil microbiota suggesting the possibility to improve the performance of this crop through the selection of genotypes improving the communities of root associated fungi, by associating and responding to beneficial fungi and repressing the pathogens.

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Bilyj, Michael. "A Study on the Phototrophic Microbial Mat Communities of Sulphur Mountain Thermal Springs and their Association with the Endangered, Endemic Snail Physella johnsoni." 2011. http://hdl.handle.net/1993/4787.

Повний текст джерела

Анотація:

The seasonal population fluctuation of anoxygenic phototrophs and the diversity of cyanobacteria at the Sulphur Mountain thermal springs of Banff, Canada were investigated and compared to the drastic population changes of the endangered snail Physella johnsoni. A new species and two strains of Rhodomicrobium were taxonomically characterized in addition to new species of Rhodobacter and Erythromicrobium. Major mat-forming organisms included Thiothrix-like species, oxygenic phototrophs of genera Spirulina, Oscillatoria, and Phormidium and purple nonsulfur bacteria Rhodobacter, Rhodopseudomonas and Rhodomicrobium. Aerobic anoxygenic phototrophs comprised upwards of 9.6 x 104 CFU/cm2 of mat or 18.9% of total aerobic heterotrophic bacterial isolates at certain sites, while maximal purple nonsulfur and purple sulfur bacteria were quantified at 3.2 x 105 and 2.0 x 106 CFU/cm2 of mat, respectively. Photosynthetic activity measurements revealed incredibly productive carbon fixation rates averaging 40.5 mg C/cm2/24 h. A temporal mismatch was observed for mat area and prokaryote-based organics to P. johnsoni population flux in a “tracking inertia” manner.

Стилі APA, Harvard, Vancouver, ISO та ін.

41

Clemente, Joyce S. "Soil Organic Matter Composition Impacts its Degradability and Association with Soil Minerals." Thesis, 2012. http://hdl.handle.net/1807/33966.

Повний текст джерела

Анотація:

Soil organic matter (OM) is a complex mixture of compounds, mainly derived from plants and microbes at various states of decay. It is part of the global carbon cycle and is important for maintaining soil quality. OM protection is mainly attributed to its association with minerals. However, clay minerals preferentially sorb specific OM structures, and clay sorption sites become saturated as OM concentrations increase. Therefore, it is important to examine how OM structures influence their association with soil minerals, and to characterize other protection mechanisms. Several techniques, which provide complementary information, were combined to investigate OM composition: Biomarker (lignin phenol, cutin-OH acid, and lipid) analysis, using gas chromatography/mass spectrometry; solid-state 13C nuclear magnetic resonance (NMR) spectroscopy; and an emerging method, solution-state 1H NMR spectroscopy. OM composition of sand-, silt-, clay-size, and light fractions of Canadian soils were compared. It was found that microbial-derived and aliphatic structures accumulated in clay-size fractions, and lignin phenols in silt-size fractions may be protected from further oxidation. Therefore, OM protection through association with minerals may be structure-specific. OM in soils amended with maize leaves, stems, and roots from a biodegradation study were also examined. Over time, lignin phenol composition, and oxidation; and aliphatic structure contribution changed less in soils amended with leaves compared to soils amended with stems and roots. Compared to soils amended with leaves and stems, amendment with roots may have promoted the more efficient formation of microbial-derived OM. Therefore, plant chemistry influenced soil OM turnover. Synthetic OM-clay complexes and soil mineral fractions were used to investigate lignin protection from chemical oxidation. Coating with dodecanoic acid protected lignin from chemical oxidation, and overlying vegetation determined the relative resistance of lignin phenols in clay-size fractions from chemical oxidation. Therefore, additional protection from chemical oxidation may be attributed to OM composition and interactions between OM structures sorbed to clay minerals. Overall, these studies suggest that while association with minerals is important, OM turnover is also influenced by vegetation, and protection through association with clay minerals was modified by OM structure composition. As well, OM-OM interaction is a potential mechanism that protects soil OM from degradation.

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Hemalatha, S. G. "Microbial associations in rice moth corcyra cephalonica staint." Thesis, 1987. http://hdl.handle.net/2009/2332.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Lee, Yi-Cheng, and 李易澄. "Associations among Various Indicators of Residential Microbial Exposures and Childhood Allergic and Respiratory Diseases." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/41799017395572832747.

Повний текст джерела

Анотація:

碩士
國立成功大學
環境醫學研究所
97
Literatures have consistently demonstrated associations between exposures to microbial agents in built environments with increasing risk of reporting respiratory diseases, mostly based on measurements of single or selected microbial agents. However, in reality, environmental microbes (e.g. fungi and bacteria and other allergens) are co-existed in any environments at all times. Therefore, study including concurrent assessment of related bioaerosols becomes essential to elucidate their individual or synergistic roles deriving at corresponding health outcomes of concerns. The aims of this study with children aged 6 to 8 is to investigate the individual and combined effects of concurrent exposures to various microbial agents, such as airborne fungal spores, viable fungi, viable bacteria, house dust associated fungal (1→3)-β-D-glucan and bacterial endotoxin, as well as house dust mite allergens, on reporting respiratory or allergic symptoms and diseases. Home characteristics are also analyzed for associations with quantitative microbial levels when appropriate to examine the potential and effective surrogates reflecting microbial exposures for prevention. Results indicate that fungal spores and Der p1 are the significant major microbial agents related to the studied health outcomes. Moreover, the moisture content of building materials (>100%), indoor and outdoor 24-hrs average temperature (<27.13℃ and <27.58℃, respectively), indoor 24-hrs average relative humidity (>63.65%), presence of irritant smells as well as higher human density can be considered as alternative or surrogate environmental indicators without actual maneuver of real sampling and analytical activity for environmental microbes. Preventive measures and priority of remedial actions can therefore be planned accordingly.

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Laughlin, Jamie B. A. "Molecular and physiological characterization of thiosulphate-oxidizing microbial associations prior to use in hydrogen sulphide biofiltration." 2000. http://hdl.handle.net/10413/4957.

Повний текст джерела

Анотація:

Interacting microbial associations capable of utilizing thiosulphate as an energy source were enriched/isolated from activated sludge, landfill site [mal covering soil and soil from an acid mine water drainage site. The isolates were designated Lf-I, Ws-2 and Am-3, respectively. Although hydrogen sulphide was the target molecule for gas biofiltration, thiosulphate, which is a key oxidized intermediate, was used in this study due to the difficulty of working with a toxic gas. Together with thiosulphate oxidation, the microbial associations were assessed for their abilities to oxidize dissolved sulphide to elemental sulphur. Physiological analyses (temperature, pH and substrate concentration optimization) were made with closed and open cultures while morphological characterization and species compositional changes were monitored by light and scanning electron microscopy (SEM). To investigate further functional and structural responses to physiological changes, denaturing-gradient gel electrophoresis (DGGE) separation of PCR-amplified 16S DNA gene fragments and Biolog GN microtitre plates were used. The associations were found to be active metabolically between 0 and 35°C, 15 and 50°C, and 15 and 45°C, with optimum temperatures of 25, 40 and 35°C for Lf-l, Ws-2 and Am-3, respectively. The optimum pH range for microbial association Lf-l was between 3 and 4. The maximum specific growth rates of associations Lf-l , Ws-2 and Am-3 were 0.08, 0.06 and 0.03 h~l , respectively. Components of all three Gram negative rod-dominated associations were motile and displayed anaerobiosis. During open culture cultivation the species complement of Lf-l , as determined by morphological analysis, changed. The same association oxidized sulphide (40 ppm) to sulphur although Ws-2 and Am-3 did not have this capacity. Biolog GN plates detected pH-effected species compositional changes in Lf-l and these were confirmed by DGGE. The same technique showed that enrichment had occurred in the Biolog GN wells. Species composition changes also resulted in response to different pH values (2 to 9), temperatures (5 to 40°C) and dilution rates (0.003 to 0.09 h-1 ), but activity changes were not always accompanied by population profile changes.
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Jia, Yinsuo. "The influence of nitrogen, phosphate and microbial associations on photosynthesis, respiration and growth in Vicia faba L." Thesis, 2010. http://hdl.handle.net/10539/7685.

Повний текст джерела

Анотація:

This project represents the development of a comprehensive description of growth in Vicia faba L. Particular attention has been paid to the impact in the tripartite legume-Rhizobium-AMF on the growth. The development of the description was divided into two parts. The first one was made up of (i) different N supply (0, 10, 25, 50, 100, 250 and 500ppm soil N) with normal P supply and (ii) different N supply (0, 10, 25, 50, 100, 250 and 500ppm soil N) with two phosphorus (0.05 and 1.6 mmol P) concentration applied and the Vicia faba seeds were planted pots filled with autoclaved river sand in order to non-producing the nodules just like normal cereal crops. As leaf nitrogen concentration (NL) increased, the quantum yield efficiency (α)，carboxylation efficiency (Ce), photon saturated net photosynthetic rats (PNmax) were converged onto a maximum asymptotic value，the Ci value fell to an asymptotic minimum. A monotonic decline in the steady-state value of Rf occurred with increasing N supply. Specific leaf area (δL) increased with increasing N supply or with increasing NL. An increase in P supply was consistently associated with an increase in N accumulation and N productivity in terms of biomass and leaf area production. Furthermore, P increased the photosynthetic N use efficiency in terms of Pmax and α. An increase in P was also associated with an increase in Ce and a decrease in Ci.. Under variable daily meteorological conditions, the values for NL, specific leaf phosphorus content (PL), specific leaf phosphorus content (PL), specific leaf area (δL), root mass fraction (Rf), PNmax and α remained constant for a given N supply during the stage of steady-state exponential growth. This study tests the hypothesis that P supply positively affects both N demand and photosynthetic NUE by influencing the upper limit of the asymptotic values for Pmax, Ce, and the lower limit for Ci in response to increasing N. The short-term photosynthetic responses to the increasing concentrations of CO2 were observed to be co-limited by both N and P supply. These findings support the proposal that the N:P supply ratio controls the plant photosynthetic capacity in response to elevated CO2 concentrations. Also, the short-term photosynthetic responses to the increasing concentrations of CO2 were observed to be co-limited by both N and P supply. The second part is tripartite symbiosis experiment with the concentration of nitrate-N for (a) the low N (LN, 10ppm N) and the high N treatments (HN, 250ppm N) without any microbial symbiotic associations;; (b) two different N supply rates plus AMF association, LNM and HNM; (c) two different N supply rates plus Rhizobium association, LNR and HNR; and (d) two different N supply rates plus both AMF and Rhizobium symbiotic associations: LNMR and HNMR. All treatments received a low level of phosphorus supply with 0.05mg P L-1 (1.61 mM NaH2PO4 ). AMF promoted biomass production and photosynthetic rates by increasing the ratio of P to N accumulation. An increase in P was consistently associated with an increase in N accumulation and N productivity, expressed in terms of biomass and leaf area. Photosynthetic N use efficiency, irrespective of the inorganic source of N (e.g. NO3‾ or N2 ), was enhanced by increased P supply due to AMF. The presence of Rhizobium resulted in a significant decline in AMF colonization levels irrespective of N supply. Without Rhizobium, AMF colonization levels were higher in low N treatments. Presence or absence of AMF did not have a significant effect on nodule mass but high N with or without AMF led to a significant decline in nodule biomass. Plants with the Rhizobium and AMF symbiotic associations had higher photosynthetic rates per unit leaf area and increased plant productivity. The plants colonized with both microbial symbionts had significantly higher total biomasses, leaf areas, the whole plant photosynthesis and respiration rates than plants with only one or no microbial symbionts. Similarly, plants with both microbial symbionts also had significantly higher growth yield (Yg ) values than all the other treatments. Maintenance respiration rates were also highest in plants with two microbial symbionts. In low N plants colonized by both microbial symbionts there was evidence of compensatory increases in the photosynthetic rates in response to the carbon sink demands of the microbial symbionts. It was shown that the plant potential photosynthetic capacity exceeds the carbon demand of the Rhizobium–AMF symbiotic associations.

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Calvo, Alegre Olga-Cristina [Verfasser]. "Interactions between non-symbiotic N2-fixing bacteria and plant roots in plant-microbial associations / presented by Olga-Cristina Calvo Alegre." 2009. http://d-nb.info/1008864501/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Дисертації з теми "Microbial association"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями