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Potgieter, Thomas. "Retention of fermentation biomass for extended L-Lysine fermentations". Doctoral thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/8786.
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Includes bibliographical references.In this thesis it was demonstrated that the current L-lysine fermentation technology can be enhanced by continuously withdrawing spent medium while recycling the biomass in the culture suspension to the bioreactor. The biomass in the reactor outlet stream is separated from the spent medium using cross-flow filtration. The objective of this thesis was to study, understand, model and optimise the performance of the L-Lysine fermentation with biomass retention using cross flow filtration. Following a review of the factors affecting cross-flow filtration and modelling approaches available, the most suitable filtration flux estimation equation was selected. The impact of filtration on microbial performance was assessed and approaches to modelling the lysine fermentation overviewed, leading to the selection of an appropriate model. Thereafter a rigorous approach to the optimisation of the biomass recycling system for lysine production was conducted and experimentally validated. A generic form of Hermia's blocking laws was found to be well suited to the description of the initial stages of cross-flow microfiltration. A constant term (the pseudo steady state flux) has been included to provide a semi-empirical correlation of the cross flow filtration flux. The pseudo steady state flux is based on Darcy's law and a combination of the shear induced diffusion and surface transport models. The presented model adequately described the experimental data. The qualitative effects of the increased hydrodynamic shear stress experienced in the filtration recycling loop on the growth, metabolism and morphology of Corynebacterium glutamicum cells have been investigated. It was found that the cell volume increases under increased hydrodynamic shear although increased shear does not alter the cell shape. The apparent specific growth rate, the yield of biomass from threonine and the specific lysine productivity of the cells exposed to hydrodynamic shear in the filtration system decreases at increased hydrodynamic shear. Using a bioreaction network (BRN) model, it was postulated that increased hydrodynamic shear causes a shift in cellular metabolism from oxidative phosphorylation to substrate level phosphorylation and glycolysis. Furthermore it is postulated that increased hydrodynamic shear causes an increase in the flux of carbon towards the cell wall to either repair or strengthen the cell wall. Fermentation models were developed based on mass and volume balances coupled to either a set of empirical correlations of the cellular metabolism developed from experimental data or a bioreaction network. The impact of filtration-associated hydrodynamic stress on the cellular metabolism was modelled based on a linear relationship between the metabolic impact and the average energy dissipation rate per unit cell mass. A critical average energy dissipation rate was identified below which no impact on the fermentation performance relative to conventional batch fermentations was detected. The fed batch fermentation with biomass recycling using cross flow filtration was optimised using an equation-based dynamic simulation package (gPROMS). The predicted optimum represented a 26% reduction in variable cost of production compared to the conventional fed-batch fermentation technology (R14.50/kg vs. R10.65/kg). The predicted optimum was physically achievable and the experimental results obtained when a fermentation was conducted at the optimal conditions corresponded well with that predicted by the proposed model. The model parameters were re-established for the industrial lysine producing strain (AEC94). At the optimum conditions the model predicted a 12% improvement in variable cost of production while a 14% improvement was realised from experimental data.
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Simpson, Kirsten Louise. "Lactobacilli from Scotch whisky fermentations : characterisation and effects on the fermentation". Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/466.
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Bates, J. A. "Factors affecting fermentation". Thesis, University of Reading, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234391.
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Minier, Michel. "Fermentation acetonobutylique par couplage a des procedes membranaires et fermentation extractive". Toulouse 3, 1987. http://www.theses.fr/1987TOU30290.
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Minier, Michel. "Fermentation acétonobutylique par couplage à des procédés membranaires et fermentation extractive". Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37608061h.
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Turon, Violette. "Coupling dark fermentation with microalgal heterotrophy : influence of fermentation metabolites mixtures, light, temperature and fermentation bacteria on microalgae growth". Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS201/document.
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La production de microalgues en hétérotrophie présente plusieurs avantages pour la production de biocarburants par rapport à la production autotrophe, comme une productivité plus importante en termes de biomasse et de lipides. Cependant, le développement industriel de ce procédé est limité par les coûts de productions associés au substrat organique (i.e. glucose) et à ceux liés à la stérilisation des fermenteurs. Les effluents de fermentation sombre, composés principalement d’acétate et de butyrate, pourraient être utilisés comme milieux de culture peu onéreux pour la culture hétérotrophe ou mixotrophe de microalgues. Les objectifs de cette thèse étaient i) de mieux appréhender la croissance algale sur des mélanges variés d’acétate et de butyrate en fonction de la présence ou l’absence de lumière et de la température de croissance et ii) d’évaluer la faisabilité d’utiliser des effluents de fermentation non stérilisés pour soutenir la croissance de microalgues oléagineuses. Tout d’abord, un modèle basé sur des bilans de masse a été construit afin de caractériser la croissance hétérotrophe de Chlorella sorokiniana et Auxenochlorella protothecoides (taux de croissance et rendements) sur des mélanges d’acétate et de butyrate. Les résultats ont montré que le rapport acétate:butyrate et la concentration en butyrate étaient deux paramètres clés pour soutenir la croissance hétérotrophe. Puis, il a été démontré que la présence de lumière et l’utilisation d’une température suboptimale (30 °C) pour la croissance algale permettaient de réduire l’inhibition du butyrate en permettant une production de biomasse autotrophe ou en améliorant la croissance sur acétate. Enfin, il a été montré que les microalgues peuvent être compétitives sur l’acétate lors de la croissance sur des effluents bruts de fermentation sombre en présence de bactéries fermentaires, grâce à la croissance rapide des microalgues sur acétate (1.75 j-1) et à un changement drastique des conditions de culture peu favorables à la croissance des bactéries d’origine fermentaireGrowing microalgae in heterotrophic mode present several advantages over autotrophic mode such as a higher productivity in terms of biomass and lipids for biofuels production. Nevertheless, this process is limited by the production cost associated with the organic substrate (i.e. glucose) and fermenters sterilization costs. Dark fermentation effluents, mainly composed of acetate and butyrate, could be used as a low-cost medium to grow microalgae heterotrophically or mixotrophically. The aims of this PhD were i) to optimize microalgae growth on various mixtures of fermentations metabolites using the presence or absence light and different cultivation temperatures and ii) to assess the feasibility of using unsterilized fermentation effluents. First, a model based on mass balance was built to characterize heterotrophic growth rates and yields when Chlorella sorokiniana and Auxenochlorella protothecoides were supplemented with different mixtures of acetate and butyrate. Results showed that the acetate:butyrate ratio and the butyrate concentration per se were two key parameters for promoting heterotrophic growth. Then, further studies showed that the presence of light and the use of suboptimal temperature (30 °C) could reduce the butyrate inhibition on growth by either triggering autotrophic production of biomass or enhancing growth on acetate. Finally, it was shown that microalgae could outcompete fermentation bacteria for acetate when growing on raw dark fermentation effluents, thanks to a fast algal growth on acetate (1.75 d-1) and a drastic change of culture conditions to the detrimental of bacterial growth
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Munro, D. Ross. "Biphasic fermentation of xenobiotics". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq20681.pdf.
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Kim, Eun-ki. "Vigorous stationary phase fermentation". Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/20710.
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Bagheri, Bahareh. "Comparative analysis of fermentative yeasts during spontaneous fermentation of grapes from different management systems". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86696.
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Thesis (MSc)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The microorganisms associated with grape berry surface can be influenced by numerous factors such as agronomic parameters. Hence, the focus of this study was comparison between three agronomic farming systems to evaluate their impact on yeast diversity. In addition, the dynamics of the yeast population throughout wine alcoholic fermentation were monitored. Three vineyards (conventional, biodynamic and integrated) were chosen and the experiment was carried out during the 2012 and 2013 vintages. A total of 600 yeast isolates including Saccharomyces and non-Saccharomyces were obtained from grape must and during different stages of fermentation including beginning, middle and end of alcoholic fermentation, from all three vineyards. Yeast species diversity in grape must and their population dynamics were evaluated by cultivating the yeasts in nutrient media and using “Polymerase Chain Reaction and sequence analysis of the ITS1-5.8S rRNA-ITS2 region. Eight, four and one species were detected from biodynamic, conventional and integrated must in 2012 vintage whereas, 2013 vintage displayed a higher diversity and 12, 11 and 9 different species were identified from biodynamic, conventional and integrated vineyard, respectively. Aureobasidium pullulans was the most frequent isolate in all three vineyards whereas Saccharomyces cerevisiae was below detection level in grape must and was only isolated in low frequencies in biodynamic must (3% of the total population) in both vintages. In general, the overlap of common yeast isolates (e.g. M. pulcherrima and H. uvarum) was observed in the musts obtained from different vineyards although unique minor species could be isolated and clearly demonstrated the distinction between the three vineyards. Moreover, biodynamic must displayed a higher degree of diversity in both 2012 and 2013 compared to the conventional and integrated vineyards. The beginning of all spontaneous fermentations was dominated by non-Saccharomyces yeast species (e.g. H. uvarum, C. zemplinina), as the fermentation proceeded, the population of non-Saccharomyces species were gradually decreased and strongly fermentative yeast S. cerevisiae dominated and completed the fermentations. The dynamics of S. cerevisiae strains was also evaluated during different stages of fermentation (beginning, middle and end), using interdelta PCR methods. A high diversity (10-18 strains per fermentation) and the sequential substitution of S. cerevisiae strains were observed throughout spontaneous fermentations. In addition, integrated vineyard displayed the highest S. cerevisiae strains compared to biodynamic and conventional vineyard.
AFRIKAANSE OPSOMMING: Die mikro-organismes wat met die oppervlak van druiwe bessies geassosieer word kan deur veskeie agronomiese faktore beїnvloed word. Gevolglik was die focus van die studie om ‘n vergelyking tussen die impak van drie verksillende boerdery sisteme op die invloed op gis diversiteit te bepaal. Die dinamiek van gis populasies tydens alkoholiese fermentasie is bykomstig bestudeer. Drie verskillende wingerde (konvesioneel, biodinamies en geïntegreerd) is gebruik vir die studie tydens die 2012 en 2013 oesjare. In total is 600 gis isolate, insluitend Saccharomyces en nie-Saccharomyces giste, verky van druiwe mos tydens verkillende fases van die fermentasie proses (begin, middle en einde) vir al drie wingerde. Die diversiteit en populasie dinamika van gis spesies in die druiwe mos is geëvalueer deur die giste in verskillendde media op te groei en ook deur die gebruik van die “polymerase ketting reaksie” (PKR) en DNS volgorde bepaling van die ITS1-5.8S rRNA-ITS2 gebied. Tydens die 2012 oesjaar is agt, vier en een afsonderlike spesies geїsoleer, in vergelyking met die 12, 11 en 9 verskillende spesies wat tydens 2013 geidentifiseer is is uit die biodinamiese, konsensionele en geïntegreerde onderskeidelik. Aureobasidium pullulans is teen die hoogste frekwensie geїsoleer in al drie wingerde, terwyl Saccharomyces cerevisiae onder die deteksie limiet was in druiwe mos en ook slegs in lae getalle in die biodinamiese mos (3% van die totale populasie) in beide oesjare. Oor die algemeen is ‘n oorvleuling tussen verwante spesies (bv. M. pulcherrima en H. uvarum) waargeneem en die mos vanaf verskillende wingerde, terwyl meer geringe spesies deurgans geїsoleer kon word en duidelik ‘n verkill tussen die drie wingerde uitgewys het. Druiwe mos uit die biodinamiese wingerd het verder ‘n hoёr graad van diversiteit en beide 2012 en 2013 vertoon as beide die konvesnionele en geïntegreerde wingerde. Die begin van alle spontane fermentasies was gedomineer deur die populasie van nie-Saccharomyces gis spesies (bv. H. uvarum, C. zemplinina), wat geleidelik afgeneem het met die verloop van die fermentasie. Die populasie van die sterk fermentatiewe, S. cerevisiae, het toegeneem tydens fermentasie en die fermentasie afgehanel as dominante gis. Die dinamika van S. cerevisiae rasse is ook geëvalueer tydens die verskillende fases van fermentasie (begin, middle en einde) deur gebruik te maak van interdelta PKR metodes. ‘n Hoё diversiteit (10-18 rasse per fermentasie) en die opeenvolgende verplasing van S. cerevisiae rasse was waargeneem deur die verloop van spontane fermentasies. Daarbenewens het die geïntegreerde wingerd die grootste getal S. cerevisiae rasse in vergelyking met die biodinamiese en konvensionele wingerde opgelewer.
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Tognete, Milena Heloisa Pozenatto Bicudo [UNESP]. "A influência da matéria-prima e diferentes cepas de levedura no rendimento fermentativo de um processo de obtenção de etanol". Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150032.
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Este estudo tem como objetivo avaliar a matéria-prima e sua influência isolada no desempenho do rendimento fermentativo de uma linhagem padrão da levedura CAT-1 testada em 31 meios de cultivos provenientes do processo de fermentação alcoólica da Usina Virgolino de Oliveira – Unidade Catanduva. Os meios foram amostrados e compostos a cada quinzena durante toda as safras 2012 e 2013. O trabalho também tem como finalidade identificar a dinâmica populacional das leveduras do mesmo processo fermentativo, através da diferenciação das linhagens por cariotipagem. As cepas isoladas foram testadas em um meio de cultivo padrão para obtenção das características tecnológicas industriais através da metodologia da Capacidade Fermentativa. Os experimentos de fermentação foram realizados nos laboratórios da Usina Virgolino de Oliveira - Unidade Catanduva em escala reduzida sempre acompanhados de um ensaio padrão utilizando meio de cultivo sintético. O primeiro ponto de estudo consistiu na caracterização da matéria-prima, mosto, e sua capacidade isolada de perturbar o Rendimento Fermentativo. Enquanto que no segundo, onde onze diferentes cepas de levedura foram identificadas ao longo das duas safras, testadas em um mesmo meio de cultivo padrão para obtenção de parâmetros industriais tecnológicos como rendimento em produto (Yp/s), rendimento em célula (Yx/s), Velocidade de consumo do substrato (Vcs), Produtividade (PROD) e Conversão (CONV) e estudada a influência no Rendimento Fermentativo. O terceiro ponto de estudo foi a comparação entre os rendimentos fermentativos obtidos experimentalmente e os rendimentos fermentativos industriais da Planta. O impacto da presença das cepas com maior rendimento em etanol foi estudado em relação aos valores de rendimento fermentativo industrial. Os resultados mostraram diferenças de desempenho da Cepa Padrão na maioria das quinzenas testadas, o que significa que há variação da matéria-prima ao longo da safra e entre as safras capazes de afetar rendimento fermentativo. Diferenças de rendimento também foram observadas entre as onze cepas nativas testadas, porém com oscilações menores e menos consideráveis do que com a matéria-prima. Os resultados obtidos em escala reduzida com base nos balanços de massa se apresentaram valores semelhantes em relação aos números de referência o que sugere que a metodologia usada para avaliar a capacidade fermentativa das cepas e a qualidade da matéria-prima foi adequada. Apesar da forte influência dos fatores estudados, não foi possível afirmar, através destes experimentos, qual deles teve papel determinante no impacto do Rendimento Fermentativo. Isso sugere que outros fatores não estudados neste trabalho estão diretamente relacionados que são capazes de influenciar o Rendimento Fermentativo.
The purpose of this study is to evaluate the sucrose mash and its influence isolated on the performance of the Fermentative Yeld of a standard strain from CAT-1 yeast tested in 31 different culture medium formulation from the Virgolino de Oliveira Plant – Catanduva Unit alcoholic fermentation process. The culture medium formulation were sampled and composed every fortnight during the whole 2012 and 2013 harvest. The work also has as purpose to evaluate the yeasts population dynamics of the same fermentative process, through the differentiation of the strains by karyotyping. The isolated strains were tested in a standard culture medium to obtain the industrial technological characteristics through the Fermentative Capacity methodology. Fermentation experiments were carried out in mill’s laboratories on a reduced scale always accompanied by a standard assay using synthetic culture medium formulation. The first point of study consisted in the characterization of the raw material, sucrose mash, and its isolated capacity to disturb Fermentative Yield. In the second, eleven different strains of yeast identified during the two harvests, they were tested in the same culture medium to obtain industrial technological parameters as Yield in product (Yp/s), Yield in cell (Yx/s), Substrate consumption velocity (Vcs), Productivity (PROD) and Conversion (CONV) and studied their influence on the Fermentative Yield. The third point of study was the comparison between the fermentative yields obtained experimentally and the industrial fermentative yields of the Plant. The impact of the presence of strains with higher Yp/s was studied in relation to industrial fermentation yield values. The results showed differences in performance of the Standard Strain in most of the fortnight tested, which means that there is variation of the raw material during the harvest and between the crops capable of affecting fermentative yield. There were also Yeld difference observed among the eleven native strains tested, but with smaller and less considerable oscillations than with the raw material. The results obtained on a reduced scale based on the mass balances were within the range expected in relation to the reference values, which suggests that the methodology used to evaluate the fermentative capacity of the strains and the quality of the raw material was adequate. Despite the strong influence of the studied factors, it was not possible to prove, through these experiments, which one had a determinant role in the Fermentative Yield impact. This suggests that other factors not studied in this work are directly related that are able to influence Fermentative Yield.
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Ulbrik, Teresa Yolanda Lustosa. "Cellulolytic fermentation by clostridium thermocellum". Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/10027.
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Kisaalita, William Ssempa. "Anaerobic fermentation of whey : acidogenesis". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27362.
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Based on the initial exploratory results of single-phase (acidogenesis and methanogenesis takes place in one vessel) whey biomethanation studies, a two-phase (acidogenesis and methanogenesis takes place in two separated serial vessels) biomethanation process was found to be more suitable for dealing with the current whey utilisation and/or disposal problem. Acidogenesis was found to be less understood in comparison to methanogenesis and therefore acidogenesis became the central problem of this thesis.
Given that 90% of the five-day biochemical oxygen demand in whey is
due to lactose, continuous culture (Chemostat) experiments were undertaken
to examine the general mechanism of lactose acidogenesis by a mixed
undefined culture using ¹⁴C-labeled tracers. Also the influence of whey protein (mainly β-lactoglobulin) on the general fermentation scheme was addressed. Experimental factors included a pH range of 4.0 to 6.5, a mesophilic temperature of 35°C and a dilution rate (D) range of 0.05 to 0.65 h⁻¹.
At a fixed pH level, the observed variability in the main acidogenic
end products (acetate, propionate, butyrate and lactate) with respect to D
were found to be a consequence of the systematic separation of the various
microbial groups involved in acidogenesis. Batch incubation of a [¹⁴C(U)]-lactate tracer with chemostat effluent samples and preparative separation of the end products followed by a liquid scintillation assay of the location of the radio activity demonstrated that a microbial population lactate to other end products and hence the observed increase in lactate
concentrations at high D values.
Further use of [¹⁴C(U)]-butyrate and [¹⁴C(2)]-propionate revealed the
predominant carbon flow routes from pyruvate to the various end products. A
qualitative lactose acidogenic fermentation model was proposed, in which
lactose is converted to pyruvate via the Embden-Meyerhof-Parnas pathway.
Pyruvate in a parallel reaction is then converted to lactate and butyrate.
In the presence of hydrogen reducing methanogens lactate is converted to
acetate in a very fast reaction and not propionate as previously believed-.
The implications of these findings with regard to optimising the acidogenic
phase reactor are discussed.
Acidogenic fermentation of protein together with lactose did not affect
the carbon flow scheme. In the D range of 0.05 to 0.15 h⁻¹ low pH (pH <
5.0) was found to favour the butyrate route at the expense of the lactate
route and at high pH (pH > 5.5) the lactate route was favoured at the
expense of the butyrate route, the pH region of 5.0 to 5.5 being the
transition range.
In order to describe the microbial growth, the Monod chemostat model was chosen among the various alternatives, because of its simplicity and its physico-chemical basis. The estimated model parameters are reported.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
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Graves, Tara. "Yeast and corn mash fermentation". Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/2099.
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Carillo-Ureta, Gabriel Eduardo. "Optimal control of fermentation processes". Thesis, City University London, 2003. http://openaccess.city.ac.uk/7584/.
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The general purpose of this thesis is to focus on a particular industrial process (from the beer industry) which serves as a guidance example for optimal control using different algorithms/methods. At the same time, the aim is to demonstrate the capabilities/features of MATLAB and SIMULINK as tools used in programming algorithms and simulation for optimal control of non linear systems. The thesis shows how to approach an optimisation problem with different techniques and to compare them on the same basis. The main reasons for carrying out research on a beer fermentation process can be summarised as follows: this kind of industry represents an up-to-date example of industrial processes in general, the need to compare and evaluate optimisation methods (well established and "modern") on similar circumstances using the sanle process model and finally, give a good foundation for the control engineer to followup this work with different optimisation techniques and/or any other industrial process. The fundamental features of the methods used involve the viability of known previously tested algorithms for optimal control of beer processes with high nonlinearity and constraints; thus testing the flexibility of some of the known MA TLAB Toolboxes for the optimal control of a particular simulated mathematical model. An important aspect of the experimentation that has been carried out, is the creation of a simulated model of a selected beer process by means of including the mathematical equations, parameters and initial conditions into an s-function block. This SIMULINK model also incorporates the particular objective function that can be calculated directly after the simulation of the process for a particular input temperature profile. Together with the use of some available MA TLAB functions for the formulation of particular optimal control techniques, this facilitates the creation of program routines that can be interfaced with the simulated process. The final results using different optimisation methods such as: the gradient method in function space, DIS OPE algorithm, Genetic Algorithms and Sequential Quadratic programming; show substantial improvement in the perfomance index obtained. The optimised temperature profiles found can be implemented for industrial application to provide a maximised ethanol production under particular restrictions, i.e. final byproducts concentration, contamination risk and brisk changes in temperature.
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McAleavey, Gervase. "Mass transfer studies in fermentation". Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356899.
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Ahmad, Mohammad Najeeb. "Mathematical modelling of fermentation systems". Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296797.
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Landon, Robert Stephen. "Optimisation of the dextran fermentation". Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333270.
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Teixeira, Miguel Monteiro. "Mixotrophic fermentation for butanol production". Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22401.
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Mestrado em BiotecnologiaThe current economy is still dominated by the fossil-based chemical industry that represents a nefarious contribution to the environment. To avoid the permanence of this industry, the necessity to optimize fermentations to cost-competitive processes started to arise. It is known that heterotrophic organisms can transform organic carbon into fermentation products with great economic interest. However, for most fermentations where sugars are used as carbon source, over one-third of the sugar carbon is lost to CO2. The CO2 evolves from the Embden-Meyerhof-Parnas (EMP) glycolysis decarboxylation reaction that converts pyruvate into acetyl-CoA. To overcome this carbon loss, one route to recapture evolved CO2 using the Wood-Ljungdahl carbon fixation pathway (WLP), in a process called anaerobic, non-photosynthetic (ANP) mixotrophy, was reviewed in the present work. The ANP mixotrophy is defined as the concurrent utilization of organic (for example, sugars) and inorganic (for example, CO2) substrates in a single organism. Comparing with the EMP glycolysis, this metabolism allows higher productivities and lower CO2 emissions during fermentations. With the purpose of increasing the biobutanol productivity in anaerobic ABE fermentations performed by Clostridium beijerickii NCIMB 8052, a genetic engineering strategy was designed to enable the ANP mixotrophic metabolism in this strain. Through a set of different fermentations and bioinformatic researches, it was concluded that Clostridium beijerickii NCIMB 8052 is not naturally capable of performing the ANP mixotrophic metabolism due to a group of genes, considered as essential for the WLP, that were found to be missing in this strain. Several cloning techniques were used to insert and overexpress, via plasmid, these genes into Clostridium beijerickii NCIMB 8052. At the end, none of the genes were successfully transformed.
Os organismos heterotróficos têm a capacidade de metabolizar carbono orgânico para gerar produtos de fermentação indispensáveis para a sociedade atual. Numa economia ainda dominada pela industria química à base de recursos fósseis, a urgência em otimizar e viabilizar os processos fermentativos é cada vez mais significativa. Em fermentações onde os açucares são utilizados como fonte principal de carbono, sabe-se que cerca de um terço do carbono proveniente do açúcar é perdido na forma de CO2. Este fenómeno deve-se a uma reação de descarboxilação, durante a via glicolítica Embden-Meyerhof-Parnas (EMP), responsável por converter o piruvato em acetil-CoA. Numa tentativa de colmatar estas perdas de carbono, o presente trabalho revê uma via alternativa para recapturar o CO2 desenvolvido usando o metabolismo de fixação de CO2 Wood-Ljungdahl (WLP), num processo chamado fermentação mixotrófica anaeróbia, não-fotossintética (ANP). O mixotrofismo ANP, definido como a utilização simultânea de substratos orgânicos (como açucares) e inorgânicos (como CO2) por um único organismo, evita as perdas de carbono, aumentando os rendimentos de produção e reduzindo as emissões de CO2 durante as fermentações. O objetivo deste trabalho foi o de tentar aumentar a produtividade de biobutanol em fermentações anaeróbias Acetona-Butanol-Etanol (ABE) realizadas pela bactéria Clostridium beijerickii NCIMB 8052. Para isso delineou-se uma estratégia de engenharia genética para ativar o metabolismo ANP mixotrófico na estirpe em causa. Através de um conjunto de diferentes fermentações experimentais e de diferentes análises bioinformáticas, concluiu-se que C. beijerickii NCIMB 8052 não é capaz de realizar o metabolismo mixotrófico ANP de forma natural e que isso se deve à ausência, no seu genoma, de um grupo de genes considerados essenciais para o funcionamento do metabolismo de WLP. Usaram-se várias técnicas de clonagem na tentativa de inserir os respetivos genes, via plasmídeo, em C. beijerickii NCIMB 8052, mas não foram obtidos os resultados esperados. Comprovou-se que nenhum dos genes de interesse foi clonado com sucesso
19
Zanganas, Panayiotis. "Fermentation methods for dextransucrase production". Thesis, Aston University, 1993. http://publications.aston.ac.uk/9693/.
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Several fermentation methods for the production of the enzyme dextransucrase have been employed. The theoretical aspects of these fermentation techniques have been given in the early chapters of this thesis together with a brief overview of enzyme biotechnology. A literature survey on cell recycle fermentation has been carried out followed by a survey report on dextransucrase production, purification and the reaction mechanism of dextran biosynthesis. The various experimental apparatus as employed in this research are described in detail. In particular, emphasis has been given to the development of continuous cell recycle fermenters. On the laboratory scale, fed-batch fermentations under anaerobic low agitation conditions resulted in dextransucrase activities of about 450 DSU/cm3 which are much higher than the yields reported in the literature and obtained under aerobic conditions. In conventional continuous culture the dilution rate was varied in the range between 0.375 h-1 to 0.55 h-1. The general pattern observed from the data obtained was that the enzyme activity decreased with increase in dilution rate. In these experiments the maximum value of enzyme activity was 74 DSU/cm^3. Sparging the fermentation broth with CO_2 in continuous culture appears to result in a decrease in enzyme activity. In continuous total cell recycle fermentations high steady state biomass levels were achieved but the enzyme activity was low, in the range 4 - 27 DSU/cm^3. This fermentation environment affected the physiology of the microorganism. The behaviour of the cell recycle system employed in this work together with its performance and the factors that affected it are discussed in the relevant chapters. By retaining the whole broth leaving a continuous fermenter for between 1.5 - 4 h under controlled conditions, the enzyme activity was enhanced with a certain treatment from 86 DSU/cm^3 to 180 DSU/cm^3 which represents a 106% increase over the enzyme activity achieved by a steady-state conventional chemostat. A novel process for dextran production has been proposed based on the findings of this latter part of the experimental work.
20
Tijjani-Oshungboye, Kubura. "Microalgae biomass as fermentation feedstock". Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1006168.
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The search for alternative energy is as a result of pollution generated by the utilization of fossil fuel. Bearing in mind the increase in demand which exceeds supply, alternative energy must reduce the carbon foot print in order to relieve use of fossil fuels. Biogas generation from wastes is an old technology that has been in existence for decades. This same concept was behind the development of the integrated algae ponding system (IAPS), where the use of microalgae biomass is adopted for waste water treatment and, anaerobic digestion which is a component of the IAPS, simultaneously generates biogas. The biogas from the IAPS was quantified in order to evaluate efficiency of the system and the anaerobic fermentation pit was also simulated in the laboratory to optimize biogas production using microalgae as co-fermentation feedstock. Microalgae biomass was evaluated as potential feedstock for ethanol fermentation and the use of biogas was investigated as an alternative transportation fuel. In an IAPS substantial biomass is produced on an annual basis. For effective treatment of waste water and efficient nutrient removal continuous harvest of the biomass is required. In the present study, water treatment efficiency of the EBRU IAPS was determined by carrying out a series of tests to investigate the decline in nutrient content from port of influent entry to effluent discharge. There was more than a 60% reduction in nutrient content with a concomitant increase in biomass and growth rate of 0.25 g/L . Biogas generated from the IAPS was quantified using a flow meter and the composition determined by gas chromatography. Methane which is the principal constituent of biogas was 75% (±SD, n=IO) and 2.34 m³.d⁻¹ was measured as biogas yield from the EBRU IAPS. The study also investigated the use of the excess microalgae biomass as a fermentation feedstock for ethanol production and as a co-substrate in order to increase biogas yield from the system. Positive results were achieved for ethanol production from microalgae although yield was generally low. About 385 mg.⁻¹ of ethanol was recovered when glucose was used as substrate, where as only 115 mg.⁻¹ of ethanol was recovered with microalgae as substrate. Suitability of microalgae as feedstock for ethanol generation and biogas generation was determined by characterisation which involved estimation of the carbohydrate, protein and lipid content, and analysis of the C, H, 0, Nand S content. Laboratory fed batch reactors simulated the anaerobic digestion process in order to study the effect of microalgae biomass as co-substrate for biogas generation. The fermenters were inoculated with an active consortium obtained from the Makana municipal waste water works and microbial studies were carried to confirm the presence of the anaerobic consortium. Different pre-treatments (concentrated, rupturing and freeze-drying) were used to disrupt the microalgae prior to introduction into fermenters in a ratio of 3: I. COD, TC, TOC, SO₄⁻² and TN analyses were carried out to monitor nutrient depletion in the system, and biogas generated by the system was quantified by volumetric analysis and the gas composition determined. Statistical analysis (ANOVA) was used to test for significant difference pre and post addition of microalgae. In the most effective fermenter, biogas production was at an average of 394 ml.d·' and CH₄ ratio in the biogas increased by over a 100%. Theoretical methane potential of the IAPS and the Makana municipal waste water works treating 5 ML.d⁻¹ of domestic waste was determined using the empirical formula of waste water and shown to yield 1,037,342.40 m³/yr. The projected biogas yield from this system was used to evaluate its potential use as transportation fuel. In total, 198,673 .55 m³ of biogas was estimated to be required to fuel the Rhodes University's fleet of vehicles, with a residual biogas stream of 838,668.85 m³. It was also demonstrated in the present study that renewable energy sourced from biomass has the potential of supplanting the use of fossil fuel resulting in less pollution leading to a cleaner and healthier environment.
21
Vendramin, Veronica. "Whey valorisation by microbial fermentation". Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3426766.
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Streptococcus thermophilus is a thermophilic lactic acid bacterium (LAB) of major importance in the dairy industry. This species is widely used as starter culture to produce fermented dairy products. It has been awarded the status of GRAS (Generally Recognized as Safe) in the USA and a Qualified Presumption of Safety (QPS) status in the European Union, due to its long history of safe use in food production. Increasing the number of starter available to producers by discovering new strains with desirable characters is important not only for identifying new properties that may better suited the needs of the industrial raising demand but also to preserve natural biodiversity, which is diminishing with the spread and overuse of commercial starters.
The progresses in high-throughput ‘omics’ technologies (‘Foodomics’) allows the development of more rational approaches aimed to improve fermentation processes both for the traditional foods productions and for new functional food products . Nevertheless, to date only few steps were made toward the in-depht analysis of the pan-genome and transcriptional regulation in species of food interest.
In this study the whole genome sequencing of eight S. thermophilus strains isolated from typical cheese-making processes in four Italian regions was performed using the Illumina platform. Genomic data were compared with the already available information in order to study the level of genetic biodiversity present within the species. In addition, some technological properties were analysed both genetically and phenotypically to integrate the knowledges at these two levels.
The applicative part of the study regarded the study of the strains during growth on milk whey, both from physiological and genetic (gene expression) standpoints. Particular effort was dedicated to production of vitamin, in particular folates. The obtained results, reported in this thesis, are interesting both from a scientific and applicative point of view.Streptococcus thermophilus appartiene ai batteri lattici (LAB) termofili ed è un microrganismo di primaria importanza nel settore caseario. Questa specie è largamente usata come starter nella produzione di prodotti caseari fermentati. Grazie alla sua lunga storia nella produzione di alimenti, gli è stato conferito lo stato di GRAS (Generally Recognized as Safe) negli Stati Uniti d’America e di QPS (Qualified Presumption of Safety) nell’Unione Europea. Aumentare il numero di ceppi starter disponibili per i produttori caseari, scoprendo ceppi autoctoni che posseggano caratteri tecnologicamente rilevanti, è importante non solo per identificare nuove proprietà che possano rispondere maggiormente alla crescente domanda, ma anche per preservare la naturale biodiversità che sta diminuendo con il diffondere e il sempre maggiore degli starter commerciali. I progressi attuali nelle tecnologie high throughput (‘Foodomics’) permettono lo sviluppo di approcci razionali per l’ottimizzazione del processo fermentativo sia nella tradizionale funzionalità alimentare sia nella nuova potenzialità dei prodotti nutraceutici. Tuttavia, non molti passi sono stati fatti verso l’analisi dettagliata della pan-genomica e della regolazione trascrizionale nelle specie di interesse alimentare. In questo studio, è stato portato a termine il sequenziamento completo del genoma di otto ceppi di S. themophilus isolati da processi di caseificazione tradizionali in varie località italiane. I dati genomici sono stati comparati con l’informazione disponibile nei database pubblici nel tentativo di studiare il livello di biodiversità genetica presente all’interno della specie. Inoltre, alcune proprietà tecnologicamente rilevanti sono state analizzate sia geneticamente sia fenotipicamente in modo da integrare le conoscenze a questi due livelli La parte applicativa dello studio ha riguardato lo studio dei ceppi durante la crescita in siero di latte, sia dal punto di vista fenotipico che dell’espressione genica, con particolare attenzione alla produzione di vitamine e specificamente di folati. I risultati ottenuti hanno prodotto informazioni interessanti sia dal punto di vista scientifico che, in prospettiva, da quello applicativo.
22
Zhao, Renyong. "Impact of sorghum proteins on ethanol fermentation and investigation of novel methods to evaluate fermentation quality". Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1036.
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Feng, Xin-Mei. "Microbial dynamics during barley tempeh fermentation /". Uppsala : Swedish University of Agricultural Sciences, 2006. http://diss-epsilon.slu.se/archive/00001186/01/xmffin0-online.pdf.
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Halidi, Ben Saida Ali. "Fermentation d'acides gras par Penicillium roqueforti". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq33669.pdf.
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Radocaj, Olgica. "Ethanol fermentation in a membrane bioreactor". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0015/MQ45840.pdf.
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Chen, Wen-Hsing. "Biological hydrogen production by anaerobic fermentation". [Ames, Iowa : Iowa State University], 2006.
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Feng, Xinmei. "Microbial dynamics during barley tempeh fermentation /". Uppsala : Dept. of Microbiology, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200659.pdf.
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Sotiriou, George K. "Effects of mixing on fermentation kinetics". Ohio : Ohio University, 1987. http://www.ohiolink.edu/etd/view.cgi?ohiou1183061483.
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Kuhlmann, C. "On the controllability of fermentation systems". Thesis, University College London (University of London), 1998. http://discovery.ucl.ac.uk/1350023/.
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This thesis concerns the controllability of fermentation processes. Fermentation processes are often described by unstructured process models. A control system can be used to reduce the effect of the uncertainties and disturbances. A process is called controllable if a control system satisfying suitably defined control objectives can be found. Controllability measures based on linear process models are identified. The idealised control objective for perfect control allows fast evaluation of the controllability measures. These measures are applied to compare different designs of a continuous fermentation process by identifying the controllability properties of the process design. The operational mode of fed batch fermentations is inherently dynamic. General control system design methods are not readily applicable to such systems. This work presents an approach for the design of robust controllers suitable for these processes. The control objective is to satisfy a set of robustness constraints for a given set of model uncertainties and disturbances. The optimal operation and design problems are combined into a single optimal control problem. The controller design is integrated into the process design problem formulation. In this way the control system and the process are designed simultaneously. Different problem formulations are investigated. The proposed approach is demonstrated on complex fermentation models. The resulting operating strategies are controllable with respect to the aims of control.
30
陳臻 i Chun Jade Chan. "Proteolytic enzyme in soy sauce fermentation". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31223977.
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Minabe, Masaharu. "The lipids of post-fermentation yeast". Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/1487.
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Burke, Frances Mary. "Fermentation development of Streptomyces thermonitrificans ISP5579". Thesis, University of Glasgow, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245820.
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Fashina, Adekunle. "Fermentation regulation for maximum downstream efficiency". Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405340.
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De, Silva L. L. S. S. K. "Lactic acid fermentation of shrimp waste". Thesis, Loughborough University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314517.
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Wilson, James Samuel. "Process intensification of hybridoma cell fermentation". Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/12155.
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Monoclonal antibodies can be produced in culture fluid by the fermentation of specificially selected hybridoma cells. Hybridoma cells exhibit suspension type fermentation characteristics and therefore the simplest method for large scale fermentation is that of the stirred tank fermenter. However, such is the growing demand for monoclonal antibodies, methods for increasing the production capacity of a commercial process are being developed. This study examines some of the current process intensification methods in relation to an established production facility. As well as examining the actual productivity increases possible with any method, the applicability of that method to a commercial environment is taken into account. Hollow-fibre systems are investigated, with a potential increase in productivity which was outweighed by the significant retooling and retraining costs. Gel Bead entrapment systems are shown to have great promise, as they can be readily placed into existing equipment and production methods. However, all methods examined, including alginate bead entrapment, were found unsuitable for hybridoma cell culture. A novel method for cell entrapment was developed, using an agarose/alginate gel mixture which allowed greatly improved growth and consistent antibody production. The entrapment method was examined in a continuous chemostatic system. This system was then scaled-up and applied to the existing facility, to give a 25L airlift operating in a chemostatic mode at a rate of 1.2-1.5 day-1.
36
Brooks, Steven. "A glucose sensor for fermentation monitoring". Thesis, Cranfield University, 1987. http://dspace.lib.cranfield.ac.uk/handle/1826/10284.
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The
evaluation, analysis and development of an
oxygen-insensitive amperometric glucose biosensor and its
application in microbial batch culture are described. The
biosensor consisted of a graphite foil electrode modified with
glucose oxidase and 1,1'-dimethylferrocene, and operated via
mediated electron transfer from the enzyme to the electrode.
Initial evaluations illustrated several
operating
characteristics which would be
expected to cause problems in
continuous
monitoring applications, most notably sensor
instability and a progressive increase in response time. The
main
underlying causes of these unfavorable characteristics were
identified as enzyme loss, mediator loss and substrate diffusion
limitation within the electrode. As a consequence of these
insights, further development of the sensor was undertaken. A
number of different electrode materials and enzyme immobilization
techniques were tested, resulting in the development of a novel
immobilization procedure using a hexadecylamine coating to bind
'the activated carbohydrate residues of periodate-oxidized glucose
oxidase.
This improved the sensor lifetime and response time
under continuous operation.
Strategies for the reliable application of the
biosensor in fermentation
monitoring were evaluated. In-line
flow cell and
in_§itu membrane probe approaches were considered,
and the latter
approach was
preferred: Considerable attention
was devoted to
optimising the design of such probes. The best
design accommodated a three electrode configuration with a
multiple biosensor array. It was found necessary to allow for
periodic on-line calibration within the aseptically operating
probe. This configuration was successfully applied on-line to
monitor glucose in batch cultures of Escherichia coli.
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Stavrinides, Alexander James. "Isothermal microwave biology : catalysis and fermentation". Thesis, Liverpool John Moores University, 2012. http://researchonline.ljmu.ac.uk/6110/.
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This thesis looks directly into the controversial subject of the microwave field effect by the production of a versatile prototype isothermal microwave reactor for the investigation of enzymatic and microbiological reactions. The observed results from the prototype reactor and experiments conducted conclude that there is a nonthermal, nonlinear response between the exposure microwave power and rate and yield of cellulose saccharification. The nature of the nonthermal response is controversial and may be dependent on the definition of "nonthermal,' leading to ambiguity of exact mechanism. Enzymatic and microbial conversion of cellulosic material to ethanol is a highly desirable industrial process. Whether the demand is for the mitigation of climate change, political obligations or energy independence, the use of arable land for energy crops limits the available glucose carbon sources for conversion to bioproducts. To prevent this limitation, cellulose (~-l,4-linked glucose polymers) are touted as the "silver bullet" to prevent carbon exhaustion or impinging on food crops. The technical constraint for the industrialization of cellulose based processing is the rate limitation in the cellulase enzymatic action on cellulose. The enzyme rate is limited by feedback cycles and limited mechanical freedom, therefore a relatively high enzyme concentration is required to speed up the process. To date, the associated enzyme production costs and infrastructure prevents bulk volume exploitation. Biomolecular advances (amino acid substitutions, recombination of expression vectors etc) have gone some way to increase either enzymatic rate or enzyme concentration. The work presented in this thesis differs by increasing the rate of the enzyme without molecular modification. Using a microwave field, the work presented shows that by separating the system into its base units, irradiation of the enzyme/substrate complex in an aqueous environment can increase both the initial enzyme rate and the saccharification yield without alteration of the temperature set point. This study shows that the rate increase is not proportional to the microwave field power. An optimal power in each study is either found or suggested. The results cited show that in the three systems (Endoglucanase and cellobiohydrolase with cellulose, endoglucanase and cellobiohydrolase and ~- glucosidase with cellulose, and ~-glucosidase with cellobiose) the initial rates can be increased by 201 %, 65.5% and 69% respectively. In the total hydrolytic process (endoglucanase and cellobiohydrolase and ~-glucosidase on a cellulose substrate) the final glucose yield was increased by 43% in comparison to the conventional thermal control reaction. This is shown in Figure 1. 10.000 1 9.000 1 8.000 j 7.000 6.000 o 20 40 60 80 100 120 140 160 180 I I 1 I U 5.000 r:: o u 4.000 3.000 2.000 j i t t , f 1.000 0.000 Time (hours) =->=OOOW Glucose' °012W Glucose ?p025W Glucose ~050W Glucose ·075W Glucose Figure 1. Microwave irradiated "cellulase" enzymes with cellulose substrate I For development into an industrial system and looking towards simultaneous saccharification and fermentation (SSF), the yeast Saccharomyces cerevisiae was subjected to irradiated microwave fermentations on a glucose substrate. Although inconclusive in terms of rate increase, cell density 1 was comparable across the power range showing that the irradiation does not have a derogatory effect. ! The natural evolution of the conclusions drawn would be development of the system into a SSF or SSCF configuration for bio-product formation is possible with irradiation up to SOW. ii The novelty of the experiments conducted is twofold. Firstly, the reactor has been designed to ensure that the microwave irradiation is independent of the bulk temperature therefore allowing the exploration of the microwave field effect independently to the thermal effect. Secondly, the microwave source is a continuous microwave irradiation (none pulse irradiation) ensuring that the reaction is subjected to the microwave field for the entire reaction.
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Saveant, Nathalie. "Étude microcalorimétrique de la fermentation homolactique". Compiègne, 1993. http://www.theses.fr/1993COMPD662.
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La technique calorimétrique a été utilisée pour l'étude de la fermentation lactique de trois souches de bactéries homofermentaires : Lactobacillus helveticus, Lactobacillus bulgaricus et Streptococcus thermophilus. On a pu dans un premier temps décrire par cette méthode les étapes physiologiques de la croissance d'une souche (L. Helveticus), puis évaluer les transferts énergétiques à partir des données expérimentales et déterminer les caractéristiques thermochimiques de cette souche. L'étude calorimétrique de l'influence de la concentration initiale en substrat montre que cette bactérie n'est pas inhibée en milieu concentré. L'étude comparative des trois souches a permis de confirmer deux points importants : le tracé du thermogramme permet de différencier, d'un point de vue cinétique et métabolique, des souches similaires appartenant au même groupe de classification, et ceci sur un milieu complexe. Un seul paramètre du thermogramme, en l'occurrence le temps de l'intensité maximale, tmax, permet de quantifier la biomasse initialement présente. Le seuil de détection de cette méthode s'avère beaucoup plus faible que celui des autres techniques analytiques utilisées. Enfin, cette méthode a permis de mettre en évidence la symbiose entre les deux souches bactériennes du yaourt, S. Thermophilus et L. Bulgaricus, et de la définir quantitativement et qualitativement. On a pu, par cette technique, spécifier que la population mixte, à concentration égale des deux souches, se comporte comme une culture pure, et déterminer la proportion des deux souches optimale pour la symbiose.
39
Lafforgue, Christine. "Fermentation alcoolique en bioreacteur a membranes". Toulouse, INSA, 1988. http://www.theses.fr/1988ISAT0024.
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Etude de la fermentation alcoolique continue couplee a la micropropagation tangentielle. La modelisation du procede permet de realiser des simulations previsionnelles et d'estimer le dimensionnement d'une installation pour une production determinee. L'application de cette technique a l'elaboration de boissons fermentees est envisagee
40
Loveland, Jennifer. "Hindgut fermentation in ruminating Holstein calves". Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49826.
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The effects of quantity of dietary starch and type of dietary protein
on hindgut fermentation were evaluated. Thirty—two Holstein bull calves
were fed diets containing variable amounts of orchardgrass hay and a grain
mixture. The amount of starch and types of protein were: [L1] low starch,
soybean meal (SBM); [L2] low starch, fishmeal plus dried brewers' grains
(FBG); [Hl] high starch and SBM; [H2] high starch, FBG. The percentages
of acid detergent fiber (ADF) and crude protein were: [L1] 19.2%, 15.1%;
[L2] 18.0%, 15.6%; [H1] 9.5%, 14.9%; [H2] 9.6%, 15.4%. After calves were
fed the diets for 17 days, they were slaughtered to obtain their
intestinal tracts. Ileal, cecal, and colonic digesta and feces of calves
fed Hl and H2 versus Ll and L2 contained less water and ADF. Concentration
of nitrogen in digesta and feces did not differ. Ileal, cecal,
and colonic digesta from calves fed H1 and H2 had significantly greater
numbers of viable anaerobic bacteria and lower pH._ Cecal digesta from
calves fed high fiber diets (L1 and L2) had lower total VFA, propionate,
and buytrate concentrations than calves fed high starch diets. Colonic
and cecal digesta of calves fed diets H1 and H2 contained less ammonia.
Acetate and propionate flux across cecal epithelium ro vrtro was faster
for diets H1 and H2. Results indicate that high dietary starch stimulated anaerobic bacterial growth and fermentation in the hindgut, and enhanced
acetate and propionate flux across the cecal epithelium. Acetate and
propionate transport across the cecal wall probably is not due solely to
passive diffusion, but it may involve a carrier. Replacement of SBM by
FBG also altered cecal fermentation to a lesser extent. Calves fed H2
had significantly greater numbers of viable anaerobic bacteria in cecal
and ileal digesta and 2 to 10 times the number of bacteria associated with
“
cecal epithelium than calves fed the other diets. Butyrate cecal concentration
and production was significantly increased when calves were
fed diets containing FBG. Cecal VFA production may account for approximately
3 to 5% of digestible energy intake.Ph. D.
incomplete_metadata
41
Trudova, Evgenia. "Xanthan Gum : Fermentation of Xanthomonas Campestris". Thesis, Malmö universitet, Fakulteten för hälsa och samhälle (HS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-18694.
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Xanthan gum is one of the most common thickening agents used worldwide.The industrial manufacturing process of xanthan gum uses cheap, carbohydrate rich mediums for fermentation of the bacterium Xanthomonas campestris. The objective of this study was to compare different fermentation mediums based on grain powder for small scale fermentation of Xanthomonas campestris. Culture mediums containing wheat or cornstarch and the less allergen prone medium containing potato starch and oat flour were investigated. All four fermentation mediums of this study showed signs of thickening, indicating the presence of alive and growing Xanthamonas campetris. Based on the growth on MacConkey and NA-agar plates, all four fermentation products showed the presence of bacteria. The fermentation product from a culture medium containing both potato starch and oat flour showed a higher concentration of bacteria compared to a culture medium containing wheat flour or cornstarch. The fermentation product in the presence of oat flour showed more than 100 times higher bacterial concentration in the fermentation product compared to wheat flour. Data suggests that potato starch and oat flour fermentation performed better than wheat flour and cornstarch and these less allergen prone mediums can be used as an alternative for fermentation of Xanthamonas campetris in the production of xanthan gum.Xantangummi är ett av de vanligast förkommande förtjockningsmedlen som används i världen.I den industriella tillverkningsprocessen av xantangummi används billiga, kolhydratrika medier för fermentering av bakterien Xanthomonas campestris. Syftet med denna studie var att jämföra olika fermenteringsmedier innehållande vetemjöl, majsstärkelse, potatisstärkelse, och havremjöl för småskalig fermentation av Xanthomonas campestris. Alla fyra fermentationsmedierna som användes i denna studie visade tecken på förtjockning, vilket indikerar närvaron av levande och växande Xanthamonas campetris. Baserat på tillväxten på MacConkey- och NA-agarplattor visade alla fyra fermenteringprodukterna närvaron av bakterium. Fermenteringsprodukten från odling i mediums innehållande både potatisstärkelse och havremjöl uppvisade en högre koncentration av bakterier jämfört med odlingsmedium innehållande vetemjöl eller majsstärkelse. Fermenteringprodukten i närvaro av havremjöl visade en mer än 100 gånger högre bakteriekoncentration jämfört med vetemjöl. Data tyder på att fermentering med potatisstärkelse och havremjöl ger bättre tillväxt än medium innehållande vetemjöl och majsstärkelse och att mindre allergenbenägna medium kan användas som alternativ för fermentering av Xanthamonas campetris vid produktion av xantangummi.
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Sotiriou, George. "Effects of mixing on fermentation kinetics". Ohio University / OhioLINK, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1183061483.
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Shu, Chin-Hang. "Multiphase bioreactors for recombinant yeast fermentation /". The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487780865408922.
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Abdul, Manan Musaalbakri. "Design aspects of solid state fermentation". Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/design-aspects-of-solid-state-fermentation(d64ea506-85ee-424f-9bca-531488e3e3c7).html.
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Solid state fermentation (SSF) refers to the microbial fermentation, which takes place in the absence or near absence of free water, thus being close to the natural environment to which the selected microorganisms, especially fungi, are naturally adapted. The current status of SSF research globally was discussed in terms of articles publication. This was followed by discussion of the advantages of SSF and the reason for interest in SSF as a notable bioprocessing technology to be investigated and compared to submerged fermentation (SmF) for the production of various added-value products. SSF also proved to be a potential technology to treat solid waste produced from food and agricultural industry and to provide environmental benefits with solid waste treatment. A summary was made of the attempts at using modern SSF technology for future biorefineries for the production of chemicals. Many works were carried out in the Satake Centre for Grain Process Engineering (SCGPE), University of Manchester, to prove the strategy of using SSF for the production of hydrolysate rich in nutrients for sequel microbial fermentation with or without adding any commercial nutrients. The research findings presented in this thesis are based on a series of SSF experiments carried out on systems varying in complexity from simple petri dishes to our own design of bioreactor systems. They were conducted to assess a solution for biomass estimation, enzymes production, and successful mass and heat transfer. A proper technique for inoculum transfer prior to the start of the fermentation process was developed. In SSF, estimation of biomass presents difficulties as generally the fungal mycelium penetrates deep and remains attached with the solid substrate particles. Although many promising methods are available, the evaluation of microbial growth in SSF may sometimes become laborious, impractical and inaccurate. Essentially, this remains another critical issue for monitoring growth. In these studies, measurement of colour changes during SSF are presented as one of the potential techniques that can be used to describe growth, complementary to monitoring metabolic activity measurement, such as CER, OUR and heat evolution, which is directly related to growth. For the growth of Aspergillus awamori and Aspergillus oryzae on wheat bran, soybean hulls and rapeseed meal, it was confirmed that colour production was directly proportional to fungal growth. This colourimetric technique was also proved to be a feasible approach for fungal biomass estimation in SmF. This new approach is an important complementation to the existing techniques especially for basic studies. The key finding is that the colourimetric technique demonstrated and provided information of higher quality than that obtained by visual observation or spores counting. The effect of aeration arrangements on moisture content, oxygen (O2), mass and heat transfer during SSF was investigated. A. awamori and A. oryzae were cultivated on wheat bran in newly designed four tray solid state bioreactor (SSB) systems. The new tray SSB systems were: (1) single circular tray SSB, (2) multi-stacked circular tray SSB, (3) Single rectangular tray SSB and (4) multi-square tray SSB. The purpose was to study the effect, on heat and water transfer, of operating variables, fermentation on the perforated base tray and internal moist air circulation under natural and forced aeration. Temperature, O2 and carbon dioxide were measured continuously on-line. Enzyme activity, moisture content and biomass were also measured. The results suggest that the air arrangements examined have a remarkable effect on the quantity of biomass produced using measurement of spores and enzymes production. The strategy presented in these studies allowed quantitative evaluation of the effect of forced internal moist air circulation on the removal of metabolic heat. With the proposed strategy, it was possible to maintain the bed temperatures at the optimum level for growth. However, the effect on moisture content was very different for the two fungi. It was found that the ability of A. oryzae to retain moisture was much higher than that of A. awamori. This is possibly due to the higher levels of chitin in A. oryzae. Greater spores and enzymes (glucoamylase, xylanase and cellulase) production was observed for A. awamori in multi-stacked circular tray and multi-square tray SSB systems compared to the conventional petri dishes and the other two systems. A. oryzae was excellent in producing protease in the same bioreactors. A direct technique of establishing a correlation between fungal growth and CER, OUR, heat evolved was proven successful in this work. The information obtained from CER and OUR led to the estimation of respiratory quotient (RQ). RQ describes the state of the fungal population in the tray SSB and gives an indication of fungal metabolic behaviour. RQ values < 1 were obtained from 38 experiments using four tray SSB systems for the two fungi. A kinetic model based on CO2 evolution instead of biomass concentration was examined in order to simplify the required experiments for kinetic model development. A Gompertz model was used to fit the integrated CO2 data and predict the quantity of CO2 evolution in all experiments. A correlation was found between the heat evolution and CER. The performances of tray SSB systems can be improved by constructing them as multi-trays. The multi-tray systems improved the mass transfer considerably compared with single tray systems. In addition, the multi-tray systems allowed precise measurement of the gradients of CO2, enzymes, spores and fungal biomass. In addition, the air arrangements using moistened air were successful in maintaining moisture content, adequate O2 supply and control of temperature, and hence, increased the productivity of both fungi. Overall A. awamori and A. oryzae have their own ability and performance to degrade and utilise the complex compositions contained in the solid substrate and fermentation conditions may lead to possible comparisons. In addition, multi-stacked circular tray and multi-square tray SSB systems demonstrated an excellent system for further investigations of mass transfer and possibly for large scale operation, though considerable optimisation work remains to be done, for example the height/diameter ratio and total number of trays should be optimised.
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Delorme, Christine. "Fermentation alcoolique en bioréacteur à membranes". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376148640.
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Chan, Chun Jade. "Proteolytic enzyme in soy sauce fermentation". Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk:8888/cgi-bin/hkuto%5Ftoc%5Fpdf?B22713384.
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Lehle, Fredric R., i Omer K. Ahmed. "Fermentation in Cotton (Gossypium hirsutum) Seeds". College of Agriculture, University of Arizona (Tucson, AZ), 1988. http://hdl.handle.net/10150/204520.
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Ethanol and acetaldehyde production by cotton seeds subjected to anoxic stress imposed by CO₂ or N₂ gas was quantified during the imbibition phase. Fermentation capacity was low in dry seeds and quickly increased during the first few hours of imbibition. In hydrated seeds, ethanol and acetaldehyde excretion following anoxic stress followed a linear trend in time. Ethanol excretion exceeded that of acetaldehyde by an order of magnitude. Similar rates of production were observed whether anoxic was imposed by either CO₂ or N₂ gas. Excreted ethanol and acetaldehyde were rapidly metabolized following alleviation of anoxic stress.
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Castro, Martinez Claudia Strehaiano Pierre Lonvaud Aline. "Brettanomyces bruxellensis". Toulouse : INP Toulouse, 2007. http://ethesis.inp-toulouse.fr/archive/00000511.
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Boudreau, Thomas F. IV. "The Effect of Fungicide Residues and Yeast Assimilable Nitrogen on Fermentation Kinetics and H2S Production during Cider Fermentation". Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/81452.
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The Virginia cider industry has grown rapidly in the past decade, and demands research-based recommendations for cider fermentation. This study evaluated relationships between the unique chemistry of apples and production of hydrogen sulfide (H2S) in cider fermentations. Yeast assimilable nitrogen (YAN) concentration and composition and residual fungicides influence H2S production by yeast during fermentation, but these factors have to date only been studied in wine grape fermentations. This study surveyed 12 Virginia-grown apple cultivars and found that the majority were severely deficient in YAN. The effects of three fungicides on cider fermentation were investigated; elemental sulfur, fludioxonil and fenbuconazole. Fenbuconazole adversely impacted fermentation kinetics. Sulfur and fludioxonil marginally impacted fermentation kinetics. Sulfur increased H2S production, but fludioxonil and fenbuconazole did not affect H2S production. There was no difference in fermentation kinetics and H2S between nitrogen sources arginine (approximating grape), asparagine (approximating apple) and ammonium (YAN supplement). Supplementation with methionine resulted in increased fermentation rate and decreased H2S production. The detrimental effects of fenbuconazole and beneficial effects of methionine were diminished with increasing total YAN. Contrary to previous findings, the most H2S was formed at 153 mg/L YAN which is above the generally recommended minimum to prevent H2S formation. These results indicate that apple juice chemistry may influence yeast metabolism during cider fermentation, in ways that have not been previously studied in grape fermentation. Our findings indicate the need for and contribute to the development of targeted fermentation management practices for cidermaking.Master of Science in Life Sciences
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Prevot, Vincent. "Comparaison de la production de complexes enzymatiques par fermentation en milieu solide et par fermentation en milieu liquide". Thesis, Reims, 2013. http://www.theses.fr/2013REIMS009/document.
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La fermentation en milieu solide est un bioprocédé pouvant éventuellement être utilisé comme technologie de rupture pour diminuer le coût des biocatalyseurs utilisés dans la conversion de biomasse lignocellulosique comme le son de blé. La première partie de ces travaux de recherche a donc étudié le potentiel de cette technologie par rapport à celle de fermentation en milieu submergé lors d'une comparaison en application. Plusieurs tests de saccharification ont ainsi été réalisés sur différentes matières premières (cellulose, son de blé) et ont permis de montrer l'avantage différentiateur des biocatalyseurs produits par fermentation en milieu solide. Ensuite, la deuxième partie de ces travaux de recherche a porté sur l'étude des facteurs de la récalcitrance du son de blé à l'hydrolyse enzymatique. Deux principaux facteurs ont ainsi pu être démontrés : un facteur physique, lié à l'accessibilité des biocatalyseurs aux polysaccharides, et un facteur biochimique, lié à l'absence ou à la faible présence de certaines activités enzymatiques (féruloyl estérase,…) dans le complexe enzymatique de Trichoderma reesei Rut-C30. Cette étude a également permis d'identifier l'origine des différentes fractions glucidiques hydrolysées et de déterminer le potentiel glucidique actuellement hydrolysable à partir de cette biomasse. Enfin, la dernière partie de ces travaux de recherche a été consacrée à l'étude pratique d'un concept innovant de procédé permettant de favoriser la conversion des polysaccharides contenus dans le son de blé. Une levée de la barrière physique au transfert de masse et par conséquent une validation de ce concept a finalement pu être réaliséeSolid-state fermentation is a bioprocess that can optionally be used as disruptive technology to reduce the cost of biocatalysts used in the lignocellulosic biomass conversion like wheat bran. The first part of this research has explored the potential of this technology compared to submerged fermentation in an application comparison. Several saccharification tests have thus been carried on different feedstocks (cellulose, wheat bran) and have shown the differentiator advantage of biocatalysts produced by solid state fermentation. Then, the second part of this research has investigated the recalcitrance factors of wheat bran to enzymatic hydrolysis. Two main factors have thus been demonstrated: a physical factor, related to the accessibility of biocatalysts to the polysaccharides, and a biochemical factor, related to the absence or the low presence of some enzymatic activities (feruloyl esterase, ...) in the enzymatic complex of Trichoderma reesei Rut-C30. This study has also identified the origin of the various carbohydrate moieties hydrolyzed and has determined the carbohydrate potential currently releasable from this biomass. Finally, the last part of this research has been devoted to the practical study of an innovative concept of process to promote the conversion of polysaccharides in wheat bran. A removal of the physical barrier to mass transfer and therefore a validation of this concept has finally been achieved