Дисертації з теми "High sugar fermentation; Saccharomyces cerevisiae"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-21 дисертацій для дослідження на тему "High sugar fermentation; Saccharomyces cerevisiae".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Riess, Julien. "Intensification de la brique « fermentation alcoolique » de substrats betteraviers (et autres substrats) pour la production d’éthanol." Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/8513/1/riess.pdf.
Повний текст джерелаFerreira, Ricardo Miguel Moura. "Adaptation of Saccharomyces cerevisiae to high pressure." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22551.
Повний текст джерелаO objetivo do presente trabalho passou pelo estudo da adaptação de S. cerevisiae à pressão, usando ciclos consecutivos de fermentação sob pressão em níveis sub-letais. Assim, este trabalho foi divido em duas partes: numa primeira parte, foram aplicadas pressões sub-letais (entre 15-50 MPa) durante o processo fermentativo para determinar as pressões a serem utilizadas na fase posterior; na segunda parte, as culturas de S. cerevisiae realizaram fermentação sob pressão ao longo de quatro ciclos consecutivos de fermentação de modo a desencadear um mecanismo de adaptação à pressão. Neste contexto, foram testadas três pressões (15 MPa, 25 MPa e 35 MPa) e duas temperaturas (30 ºC e temperatura ambiente). De modo a monitorizar os processos, foram determinadas as concentrações de açúcares (glucose, frutose e maltose), etanol e ácidos orgânicos (cítrico, málico, succínico e acético). Para além disso, foram realizadas análises microbiológicas para determinar a viabilidade celular e concentração de biomassa. Após cada ciclo a 15 e 25 MPa, tanto o crescimento celular como a produção de etanol mostraram tendência para aumentar, sugerindo a adaptação da S. cerevisiae a estes níveis de pressão. Na verdade, no final do 4º ciclo sob ambas as pressões, a produção de etanol foi superior à observada à pressão atmosférica (8.75 g.L-1 e 10.69 g.L-1 a 15 e 25 MPa, respetivamente, comparando com 8.02 g.L-1 à pressão atmosférica). No entanto, quando a pressão aumenta para 35 MPa, o crescimento celular e a produção de bioetanol diminuíram, sendo mínimas após os 4 ciclos de fermentação consecutivos. De um modo geral, estes resultados sugerem que a adaptação a condições sub-letais de pressão (15 e 25 MPa) pode melhorar a produção de bioetanol pela S. cerevisiae, podendo esta técnica ser utilizada para aumentar rendimentos e produtividades da fermentação alcoólica
The objective of the present work was to study the adaptation of S. cerevisiae to the pressure, using consecutive cycles of fermentation under pressure at sublethal levels. Thus, this work was divided in two parts: in the first part, sublethal pressures (between 15-50 MPa) were applied during the fermentation process to determine the pressures to be used in the later phase; in the second part, S. cerevisiae cultures underwent fermentation under pressure over four consecutive fermentation cycles to trigger a pressure adaptation mechanism. In this context, three pressures (15 MPa, 25 MPa and 35 MPa) and two temperatures (30 ° C and ambient temperature) were tested. In order to monitor the processes, the concentrations of sugars (glucose, fructose and maltose), ethanol and organic acids (citric, malic, succinic and acetic) were determined. In addition, microbiological analyses were performed to determine cell viability and biomass concentration. After each cycle at 15 and 25 MPa, both cell growth and ethanol production showed a tendency to increase, suggesting the adaptation of S. cerevisiae to these pressure levels. In fact, at the end of the 4th cycle under both pressures, the ethanol production was higher than that observed at atmospheric pressure (8.75 g.L-1 and 10.69 g.L-1 at 15 and 25 MPa, respectively, comparing with 8.02 g.L-1 at pressure atmospheric). However, when the pressure increases to 35 MPa, cell growth and bioethanol production decreased, being minimal after the 4 consecutive fermentation cycles. In general, these results suggest that adaptation to sublethal pressure conditions (15 and 25 MPa) can improve bioethanol production by S. cerevisiae, and this technique can be used to increase yields and yields of alcoholic fermentation.
Cyr, Normand. "Effect of aeration strategy on the performance of a very high gravity continuous fuel ethanol fermentation process." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100789.
Повний текст джерелаGlycerol plays an important role in maintaining the redox balance within the cells by oxidizing the cytosolic NADH under anaerobic conditions. It is also believed that it acts as an osmoprotectant and would be favourably produced in high osmotic pressure conditions.
In order to mitigate the production of glycerol, various aeration strategies were investigated in a single-stage continuous fermentation system. Oxygen dissolved in the fermentation medium put the yeast in aerobiosis, acted as an oxidizing agent and hence minimised the specific glycerol production by 36% as compared to a completely anaerobic fermentation.
This has hardly been reproduced in a more industrially relevant system using a multi-stage continuous fermentation process. Indeed, oscillations in the concentrations of the various metabolites over time made difficult the assessment of significant changes. Nevertheless, these findings open the door to further investigations in order to understand the effect of oxygen in continuous fermentations using very high gravity feeds, such as in the fuel ethanol industry.
Brey, Stephan. "High gravity brewing - its effect on hydrophobic polypeptide losses and proteinase a secretion by Saccharomyces cerevisiae during wort fermentation." Thesis, Heriot-Watt University, 2004. http://hdl.handle.net/10399/366.
Повний текст джерелаWestman, Johan. "Ethanol production from lignocellulose using high local cell density yeast cultures. Investigations of flocculating and encapsulated Saccharomyces cerevisiae." Doctoral thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3685.
Повний текст джерелаAkademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 19 februari 2014,klockan 13.30 i KA-salen, Kemigården 4, Göteborg.
Younis, Omar Stephan. "Wort maltose content : its effect on volatile production and fermentation performance by Saccharomyces cerevisiae and applications in high gravity brewing." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/482.
Повний текст джерелаCarvalho, Joao Carlos Monteiro de. "Influência de vazão exponencialmente decrescente do mosto de melaço de cana-de-açucar no processo descontínuo alimentado de fermentação alcoólica." Universidade de São Paulo, 1990. http://www.teses.usp.br/teses/disponiveis/9/9135/tde-18032008-142642/.
Повний текст джерелаThe fed-batch ethanol fermentation of sugar-cane blackstrap molasses by the action of Saccharomyces cerevisiae (pressed yeast) was studied. The influence of exponencialy decreasing feeding rates and of the fermentor filling up time on the system behavior was analysed considering the following parameters: 1. ethanol and cell productivities, 2. ethanol yield and 3. cell growth ratio.
Furlan, Renata Maria Christofoleti. "Seleção de leveduras para a fermentação com alto teor alcoólico a partir da biodiversidade encontrada em destilarias brasileiras." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/11/11138/tde-20092012-084932/.
Повний текст джерелаBrazil is the second largest ethanol producer and one of the leading ethanol exporter in the world, and this biofuel has great impact on the country economy. Huge demand is expected for this product, not only to supply the growing domestic consumption but due to the end of the United States market protectionism. In view of this, Brazil should produce more ethanol and at a lower cost to maintain competitiveness in relation to fossil fuels. One of the technological approaches which emerges is the high ethanol content fermentation. However, one of the limiting factors for this technology is the absence of proper strains to face the very harsh fermentation condition, where several stresses are simultaneously imposed to the fermenting yeast. This work aimed at selecting Saccharomyces cerevisiae strains from the biodiversity of yeasts found in Brazilian distilleries to conduct high ethanol fermentation with cell reuse. The selection strategy was to search for multiple tolerant strains to ethanol, acid, osmotic and thermal stresses. For that, a total of 525 strains, which were obtained from several distilleries, were subjected to a selection in order to highlight multi-tolerant strains. About half of these strains were subjected to a pre-screening procedure to evaluate growth (O.D.570nm, for 24 hours at 30ºC) in medium containing molasses and sugarcane juice (25% TRS), and 200 strains were selected. These 200 strains, together with 249 strains not previously evaluated, were screened in a medium imposing multiple stresses (ethanol, acid, osmotic and thermal). This medium was chosen after assessments of 26 different medium formulations with the above mentioned stresses and with different intensities. The purpose of that was to find a medium which best discriminate the tolerance of the reference yeasts: PE-2 and bakery Saccharomyces cerevisiae strains, with and without ability to persist in the industrial process, respectively. The strain tolerance was evaluated by biomass formation (O.D.570nm, for 24 hours at 30ºC). By this mean 34 strains were selected displaying similar or superior performance in comparison with PE-2 strain. These strains were then assessed for cell viability and growth in cell reuse fermentations (10 cycles), using cane juice/molasses substrates with increasing sugar content, at 30ºC, reaching 15-16% ethanol (v/v). The 10 strains with the best performances were subjected to final evaluation in fermentations simulating the industrial process with cell reuse, at 32ºC, using the same substrate with increasing sugar content, which allowed rises in ethanol content from 11 to 15% (v/v) over the cycles. For this final evaluation, the following parameters were determined: ethanol yield, biomass and glycerol formation, residual sugar levels, cell viability and storage carbohydrate levels (trehalose and glycogen). At least four strains showed superior fermentative attributes to reference strain (PE-2), leading to the conclusion that strains able to conduct high ethanol content fermentations can be obtained from the natural biodiversity found in Brazilian distilleries.
Ishola, Mofoluwake M. "Novel application of membrane bioreactors in lignocellulosic ethanol production : simultaneous saccharification, filtration and fermentation (SSFF)." Doctoral thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3705.
Повний текст джерелаThesis for the degree of Doctor of Philosophy at the University of Borås to be publicly defended on 31 October 2014, 10.00 a. m. in room E310, University of Borås, Allégatan 1, Borås.
Carvalho, Joao Carlos Monteiro de. "Contribuição ao estudo dos processos descontínuo e descontínuo alimentado de fermentação alcoólica." Universidade de São Paulo, 1994. http://www.teses.usp.br/teses/disponiveis/9/9134/tde-22102007-115732/.
Повний текст джерелаThe batch and fed-batch fermentations of sugar -cane blackstrap molasses by the action of Saccharomyces cerevisiae(pressed yeast) were studied. The influence of exponentially decreasing feeding rates, fermentar filling-up time and levei of inocullum on the behavior was analysed considering the following parameters: - ethanol and cell productivities - ethanol yield - yield yeast. At fed-batch fermentation, the maximum ethanol productivity obtained was 16.9 g/L.h. The results of ethanol productivities and yield achieved for batch and fedbatch (with fermentar filling-up time of 3 h and time constant of 1.6 h-1
Varize, Camila de Souza. "Aumento da tolerância de Saccharomyces cerevisiae a fatores estressantes da fermentação etanólica: linhagens modificadas e suplementação de aminoácidos." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/11/11138/tde-03052018-112458/.
Повний текст джерелаThe expansion biofuels participation in the world energy matrix would help to extend the existence of fossil fuel reservoirs, mitigate the threats of climate change, and enable a better security of energy supply. The Brazilian process of ethanol production from sugarcane has gained an important role in the global energy scenario, for the high yield and low production cost. S. cerevisiae species is widely used in industrial fermentations for being resistant, but the Brazilian process imposes a variety of stressing factors to the yeast, affecting its metabolism and growth. The Very High Gravity Fermentation is performed by the utilization of musts with high sugar concentration and is one of the most efficient ways for obtaining high ethanol levels. However, this technology causes additional deleterious effects to the yeast. In this context, increasing yeast tolerance is of fundamental importance for a satisfactory fermentative performance. In this study we assessed S. cerevisiae strains - isogenic to the industrial strain CAT-1 - with over expression of TRP1 and MSN2 genes involved to tryptophan biosynthesis and in general stress response, respectively. These strains were evaluated for their potential to perform fermentations with high ethanol content, simulating the conditions of Brazilian distilleries. The results showed that the MSN2 gene in the truncated version improved strain mainly to respond to the osmotic stress, increasing in fermentation velocity and the consumption of sugars. The TRP1 gene overexpression promoted higher growth in YEPD medium with 8% ethanol, however, decreased viability at concentrations above this level. The present work also evaluated the effect of amino acid supplementation on the physiology of the CAT-1 strain in YNB medium and in molasses and syrup of sugarcane. Histidide supplementation increased the growth and cell viability in the different media tested. In addition to histidine, the amino acids lysine and alanine increased the growth of CAT-1 in molasses. Supplementation of tryptophan and asparagine also promoted increased cell viability in sugarcane syrup. On the other hand, in microplate assays, cysteine supplementation decreased growth in YNB medium with 10 and 12% ethanol, and in molasses with 20% ART. The results indicate that both genetic engineering and amino acid supplementation may be viable alternatives to increase tolerance of S. cerevisiae to supporting multiple stress conditions typical in Brazilian distilleries.
Lopes, Lucas Souza. "Caracterização molecular da Linhagem Pedra 2 de Saccharomyces cerevisiae sob condições de alto etanol em fermentadores industriais." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/11/11137/tde-13012015-135135/.
Повний текст джерелаThe Pedra-2 (PE-2) strain of Saccharomyces cerevisiae is commonly used in the industrial process for biofuel production. In studies of wild type strains of S. cerevisiae, a wider tolerance to ethanol was achieved, which allowed for the development of a new technology of high alcohol percentage fermentation. This process made possible the increase of total sugar concentration in the mixture, and the volume of purified ethanol, although the new process has caused increase in the stresses applied to the yeast. In this study, the transcriptional profile of the PE-2 strain in high ethanol conditions is presented using DNA microarray. The global expression profile was used to identify groups of genes of interest and to analyze metabolic pathways that became co-regulated in adaptation to stress conditions imposed to the yeast by the industrial fermentation. In particular, 5860 genes were studied in this work and were detailed according to their expression profiles belong the fermentation cicle (0, 6, 12 and 18 hours). Moreover, metabolic pathways associated to key compounds in the fermentative process were described in terms of the composition of the differentially expressed genes. In addition, groups of genes highly correlated to different biological process in S. cerevisiae were identified. Finally, it is expected that this work could provide new directions in the study of fermentative efficiency and induced stress adaptation during the industrial fermentative process.
Alexandrino, Natalia. "Melhoramento de leveduras para fermentação com alto teor alcoólico mediante hidridação e evolução adaptativa." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/11/11138/tde-20092012-084510/.
Повний текст джерелаEthanol contributes significantly to the energy country matrix, which presents itself as extremely favorable to the share of renewable energy. The demand for this biofuel is increasing and technologies for its production in a sustainable way is of paramount importance such as fermentation with very high gravity, already used in some countries. Yeast strains tolerant to multiple stresses greatly contributed to the deployment of such technology in Brazil. In this context the present work is inserted, which seeks yeast strains capable of withstanding the stresses imposed by high ethanol content fermentation. In order that, three of the best industrial strains of Saccharomyces cerevisiae currently available (CAT-1, PE-2 and SA-1), were used in a program to select hybrids with tolerance towards multiples stresses: ethanolic, osmotic and acid, besides other factors involved in a high ethanol content fermentation. These strains were sporulated and dissected to obtain haploid cells, which were submitted to inter- and intra-strains crossings. Hybrids from polycrossings (random crossings) were subjected to an adaptative evolution in media with increasing stressing action over the course of 80 generations. At the end of evolution, prevalent variants were sought in the hybrids population, and submitted to new selective procedures with several stressing conditions. In the same way, directed crossings (between identified haplois) were performed by micromanipulation, and the resulting hybrids were subjected to the same selective procedure. Therefore, from 230 haploid from the 3 parent strains, 174 were isolated (120 from polycrossings and 54 from directed crossings) and pre-selected for higher tolerance in selective media; moreover their karyotypes were established by electrophoretic karyotyping. Strains showing greater tolerance (27) were again evaluated during cell recycling fermentations with high ethanol content (up to 14.5% v/v) using must formulated with water and molasses. At all stages, the isolates were compared with the parental strains (CAT-1, PE-2 and SA-1), and at the end of the selection process, the strain 35B (hybrid between CAT-1 and PE-2) standed out with fermentative attributes higher than the parentals. The fermentative performance was assessed by biochemical, physiological and technological parameters (ethanol efficiency, cell viability, biomass gain, glycerol formation and cellular levels of reserve carbohydrates - glycogen and trehalose). The results suggest that due to desirable fermentation traits, the hybrid 35B, could be used as starter in industrial fermentation process with high ethanol content.
Gomes, Elenice Mendes Silva. "Influência das concentrações de açúcares nos mostos sobre o desempenho da fermentação etanólica conduzida em batelada alimentada com vazão variável de alimentação." Universidade Federal de Alagoas, 2011. http://www.repositorio.ufal.br/handle/riufal/1202.
Повний текст джерелаFundação de Amparo a Pesquisa do Estado de Alagoas
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Este estudo objetivou avaliar a influência das concentrações de açúcares nos mostos, sobre o desempenho da fermentação etanólica conduzida em batelada alimentada com vazão variável de alimentação, para a definição das melhores concentrações de ART nos mostos (de caldo, de melaço e misto) que conduzam a melhores eficiências de fermentação e produtividade em etanol. Na preparação do mosto misto foram utilizadas as seguintes proporções (20% melaço + 80% caldo, 40% melaço + 60% caldo, 50% melaço + 50% caldo, 60% melaço + 40% caldo, 80% melaço + 20% caldo). O perfil de alimentação foi decrescente, variando-se a vazão de 0,75 a 0,25 L.h-1, com tempo de enchimento do fermentador de 3 horas para todos os ensaios, variando-se de 30 em 30 minutos a vazão de alimentação de mosto, em fermentador de 4L de volume de trabalho (3 litros de mosto e 1 litro de inoculo), avaliando-se diferentes concentrações de ART nos 3 tipos de mosto estudados. Foram avaliados parâmetros de desempenho, como eficiências fermentativa e de processo e produtividade em etanol. Nos mostos foram quantificados pH, acidez sulfúrica, Brix e ART. No meio fermentado (vinho), pH, acidez, Açúcares Residuais e teor de etanol e quantidade de células. O perfil cinético foi definido, quantificando-se as concentrações de células, substrato e etanol (em intervalos de 1 hora). Os valores indicados neste estudo, como ponto de partida para utilização industrial, são Brix de 16 a 18 (ART 114,25 a 125,86 g/L), de 14 a 18 °Brix (ART de 112,90 a 141,24 g/L) e próximo de 16 °Brix (ART de 113,68 g/L a 123,30), respectivamente para mostos de melaço, caldo e misto (caldo + melaço). As eficiências de fermentação foram: 77,17 a 90,30%, para mosto de caldo, 74,4 a 86,51% para mosto misto e 61,84 a 84,06 para mosto de melaço. As produtividades obtidas foram 6,85 a 8,21g/L.h, para mosto de caldo, 5,90 a 7,77g/L.h para mosto misto e 4,04 a 6,72g/L.h para mosto d melaço. Estas faixas recomendadas servem para subsidiar, como ponto de partida, a condução da fermentação etanólica industrial conduzida em batelada alimentada com vazão variável de alimentação, visto que as condições de condução dos ensaios, assim como as matérias-primas utilizadas na preparação dos mostos, foram semelhantes às utilizadas industrialmente.
Nguyen, Trung Dung. "Determination of the genetic basis for successful fermentation in high sugar media." Thesis, 2014. http://hdl.handle.net/2440/92547.
Повний текст джерелаThesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2014
Bai, Fengwu. "Process Oscillations in Continuous Ethanol Fermentation with Saccharomyces cerevisiae." Thesis, 2007. http://hdl.handle.net/10012/2771.
Повний текст джерела"Effect of dissolved carbon dioxide on very-high-gravity fermentation." Thesis, 2012. http://hdl.handle.net/10388/ETD-2012-08-540.
Повний текст джерелаCHIEN, WAN-SHAN, and 簡萬山. "Effect of aeration on the ethanol production by Saccharomyces cerevisiae in very-high-gravity(VHG) fermentation." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/23038051952144613315.
Повний текст джерела大同大學
生物工程學系(所)
97
Controlling the level of dissolved oxygen in fermenting medium is essential in ethanol production. Since the traditional DO sensor failed to monitor anaerobic fermentation by detecting the significant value at low amount of dissolved oxygen, ORP sensor was utilized as a new delicate method to monitor the slight change of oxygen level, furthermore, to control the level of dissolved oxygen during yeast fermentation. Comparing to DO sensor, ORP sensor offered more flexibility and the management to control different ORP levels which played a significant role in ethanol industry by increasing activity of yeast, enhancing ethanol yield coefficient and average ethanol productivity, and reducing residual glucose concentration. Nine groups of ethanol fermentation studies were conducted using glucose baths of the concentrations of 300, 250, and 200 g/L, parameters of ORP -150, -100 mV by injecting slight different amount of air and uncontrolled ORP as negative control group. The results showed the best ethanol yield coefficient was achieved at -150 mV of ORP, and average ethanol productivity was increased at -100 mV of ORP. Taken both factors into consideration, the group using 250 g/L glucose with -100 mV of ORP had better performance, in which the ethanol yield coefficient was increased by 2% to 0.477, comparing to that of control group 0.467. Average ethanol productivity was increased by 25% to 4.073 g/L/hr, comparing to that of the control group 3.262 g/L/hr. During very-high-gravity ethanol fermentation using 300 g/L glucose, considering the influence of aeration in different phases of yeast growth and the different injection levels of air on the productivity of ethanol, it was found in log phase of cell growth (after 8-18 hr fermentation), with 820 ml/min air injection, ethanol yield coefficient maintained the same as that of control group (0.439) and average ethanol productivity was increased by 142 % to 3.737 g/L/hr, comparing to that of the control group 2.624 g/L/hr.
林自威. "High cell density fermentation of recombinant saccharomyces cerevisiae and pichia pastoris for the expression of aspergius niger glucose oxidase." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/03831959964940730890.
Повний текст джерела國立臺灣科技大學
化學工程系
92
High cell density fermentation of recombinant yeasts Saccharomyces cerevisiae and Pichia pastoris were studied. Both recombinant yeasts strains carry glucose oxidase(GOD) gene of Aspergius niger and constitutively express this extracellular enzyme. Among the carbon sources screened, fructose is the one very suitable for cultivating both GOD expressing recombinant yeasts. Fed-batch cultivation was employed to achieve high cell density fermentation. When 20﹪(w/v) fructose was used in the feeding nutrient and exponential feeding strategy was employed for S. cerevisiae high cell density cultivation, 200 OD600 was obtained after 66 hours cultivation and the final GOD activity was 107 U/ml. Under the same cultivation condition, cell concentration of P. pastoris could reach 220 OD600 and the GOD activity could only reach 40 U/ml. In order to prevent the extracellular GOD from being degraded by protease, 1﹪ casmino acid was employed in the medium. The cell density of P. pastoris could be increased further to 365 OD600 , when 40﹪ fructose was used in the feeding medium. The GOD activity of 85 U/ml was obtained. GOD from S. cerevisiae and P. pastoris had very different glycosylation extent. Glycosylation degree of GOD(S. cerevisiae) and GOD(P. pastoris) were 104﹪ and 25﹪, respectively. The high glycosylation extent of GOD(S. cerevisiae) make it has broader pH and temperature stability range than that of GOD(P. pastoris). The molecular weight of GOD(S. cerevisiae) and GOD(P. pastoris) were determined to be about 140 KDa and 90 KDa , respectively.
TSAI, WAN-JUAN, and 蔡宛潤. "Improvement of fermentation ability in high temperature by homologous recombination of heat shock protein 104 promoter of saccharomyces cerevisiae Kyokai 7." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/gbgwqa.
Повний текст джерела國立中正大學
化學工程研究所
105
In industry, simultaneous saccharification and fermentation (SSF) is considered to be an important process for the production of alcohol. Because it can efficiently reduce the cost of the production of cellulosic bioethanol. Unfortunately, the temperature for cellulose saccharification is higher than that for yeast fermentation. Therefore, it is desirable to develop a thermotolerance yeast strain to be adopted in the SSF process. When exposed to a variety of environmental stresses such as high temperature, alcoholic or oxidative stress, yeasts rapidly produces trehalose and heat shock proteins (HSPs). In the case of high temperature stress, the hydrogen bonding and Van der Waals force inside proteins can be destroyed then leading their denaturation. The increased misfolding proteins then induced expression of HSPs to help protein refolding and the survival of the cells. Among HSPs, HSP104 is essential for cell survival under high temperature. However, the induction of HSP104 is only transient by which the cells would not be able to survive after a long period of high-temperature fermentation. To prolong the expression of HSP104 at high temperature, plasmid pTEF1-2μ ori HSP26P ISA1 40homo was constructed and the NDA fragment 40homo-FRT-HSP26p-40homo amplified using polymerase chain reaction transformed to Saccharomyces cerevisiae for substituting the HSP104 promoter for the HSP26 promoter using homologous recombination.
Guimarães, Pedro M. R. "Physiology of yeasts in alcoholic fermentation processes." Doctoral thesis, 2008. http://hdl.handle.net/1822/8608.
Повний текст джерелаThis thesis is focused on physiological aspects of the yeasts used in two alcoholic fermentation processes: primary brewing fermentation and fermentation of lactose (particularly lactose derived from cheese whey) to ethanol by recombinant Saccharomyces cerevisiae flocculent strains. The brewing fermentation is probably the most extensively studied alcoholic fermentation process. Nevertheless, developments in brewing technology demand deeper understanding of yeast physiology under process conditions. The studies with brewer’s yeast reported in this thesis addressed two specific questions that had not yet been effectively investigated. First, it is here directly demonstrated for the first time that the brewer’s yeast lipid composition, particularly the amounts of sterols and unsaturated fatty acids, affects the activity of maltose transporters. The maltose uptake rates were correlated with the amount of ergosterol in yeast, showing that proper function of the maltose permeases requires adequate amounts of ergosterol in the plasma membrane. This effect may partly explain the low maltose (and maltotriose) transport rates at the beginning and during the second half of brewery fermentations, when the sterol content of the yeast is low. Second, the energetic state of the yeast was studied under the specific environments of high- and very high-gravity brewing fermentations. The adenylate energy charge (EC) of the yeast was high (>0.8) throughout fermentation until residual sugar concentrations became low and specific rates of ethanol production became less than 5% of the maximum values observed in early fermentation. At that point, the EC fell to around 0.5 – 0.6. The results suggest that the ethanol tolerance of brewer’s yeast is high so long as fermentation continues. However, when residual α-glucoside concentrations no longer support adequate rates of fermentation both the EC and the yeast viability collapse. The development of microorganisms that efficiently ferment lactose has a high biotechnological value for the design of processes for the bioremediation of cheese whey with simultaneous production of bio-ethanol. A new lactose-fermenting flocculent S. cerevisiae recombinant strain is described here. This strain (T1-E) was obtained by evolutionary engineering of an original recombinant (T1, constructed in previous work) that had shown rather poor lactose fermentation and flocculation performances. The new strain T1-E consumed lactose 2-fold faster producing 30% more ethanol than T1. Its flocculation performance was also significantly better than that of T1. A series of physiological and genetic studies were done to compare T1 and T1-E. The contribution of the identified molecular differences to the improved lactose fermentation phenotype of strain T1-E is discussed. In batch fermentations with mineral medium, the new strain T1-E consumed rapidly and completely lactose at initial concentrations up to 150 g•L-1. The maximum ethanol titre reached was 8% (v/v) and the highest ethanol productivity was 1.5 – 2 g•L-1•h-1. T1-E was also able to ferment 3-fold concentrated cheese whey (about 150 g•L-1 of lactose), producing 7% (v/v) of ethanol. These results demonstrate that T1-E is the most efficient lactosefermenting S. cerevisiae recombinant strain reported in the literature. Being highly flocculent, this strain is suitable for developing high cell density fermentation systems that, when operated in continuous with flocculated biomass retention, can reach very high productivities. Sugar transport is a key factor determining fermentation efficiency in both processes studied in this thesis. Studies of lactose transport by the recombinant S. cerevisiae strains (T1 and T1-E) and by Kluyveromyces lactis revealed that zero-trans uptake rates of lactose measured by standard methodology (i.e. using suspensions of yeast harvested from fermentation, washed and stored in nutrient-free buffer at low temperature before they are assayed using radiolabeled sugar) were too small (by factors of 3 to 8) to account for the lactose consumption rates observed during fermentations. A short incubation (1 – 7 min) with glucose (10 – 30 mM) increased the low intracellular ATP and EC of cells in the starved yeast suspensions to the levels found in actively fermenting yeast cells, and simultaneously increased the activity (Vmax) of the lactose transporters by factors of 1.5 to 5. Similar observations were made for maltose transport in brewer’s yeasts. These results suggest that the electrochemical proton potential that drives transport through sugar/H+ symports is significantly smaller in the starved yeast suspensions used for the zero-trans assays than in actively metabolising cells. Short exposure of the starved cells to glucose is suggested as a quick method to approach more closely the sugar/H+ symport capacity of the actively fermenting cells.
Esta tese foca-se em aspectos relacionados com a fisiologia de leveduras utilizadas em dois processos de fermentação alcoólica: a fermentação primária da cerveja e a fermentação de lactose (em particular a lactose derivada do soro do queijo) para produção de etanol por estirpes floculantes de Saccharomyces cerevisiae geneticamente modificadas. A fermentação da cerveja é provavelmente o processo de fermentação alcoólica mais extensivamente estudado. Todavia, o desenvolvimento da tecnologia para o fabrico de cerveja requer uma compreensão mais aprofundada da fisiologia da levedura nas condições específicas deste processo. Os estudos com levedura de cerveja descritos nesta tese abordaram duas questões específicas que não haviam ainda sido efectivamente investigadas. Em primeiro lugar, é aqui demonstrado pela primeira vez que a composição lipídica da levedura de cerveja, em particular o seu conteúdo em esteróis e ácidos gordos insaturados, afecta a actividade dos transportadores de maltose. Verificou-se uma relação entre as taxas de transporte de maltose e a quantidade de ergosterol na levedura, demonstrando que o funcionamento adequado das permeases da maltose requer quantidades adequadas de ergosterol na membrana plasmática. Este efeito poderá explicar parcialmente as baixas taxas de transporte de maltose (e maltotriose) no início e durante a segunda metade das fermentações de cerveja, fases em que o conteúdo de esteróis da levedura é baixo. Em segundo lugar, o estado energético da levedura foi estudado nas condições específicas de fermentações de cerveja com mostos de alta e muito alta gravidade. A carga energética (EC) da levedura foi elevada (>0.8) durante a fermentação até a concentração residual de açúcar se tornar baixa e as taxas específicas de produção de etanol baixarem para menos de 5% dos valores máximos observados na fase inicial da fermentação. Nesse ponto, a EC decaiu para cerca de 0.5 – 0.6. Os resultados sugerem que a tolerência da levedura de cerveja ao etanol é elevada enquanto a fermentação prosseguir. No entanto, quando as concentrações residuais de α-glucosídeos não mais sustentam taxas de fermentação adequadas tanto a EC como a viabilidade da levedura colapsam. O desenvolvimento de microrganismos que fermentem de forma eficiente a lactose tem um elevado valor em termos biotecnológicos para o desenho de processos para a biorremediação do soro do queijo com produção de bio-etanol em simultâneo. Uma nova estirpe recombinante de S. cerevisiae capaz de fermentar a lactose e floculante é descrita nesta tese. Esta estirpe (T1-E) foi obtida por evolução dirigida a partir de uma estirpe recombinante original (T1, construída em trabalho prévio) que havia demonstrado um fraco desempenho em termos de fermentação de lactose e de floculação. A nova estirpe, T1-E, foi capaz de consumir a lactose duas vezes mais rapidamente e de produzir 30% mais etanol do que a estirpe T1. Foram efectuados vários estudos fisiológicos e genéticos para comparar as estirpes T1 e T1-E. A contribuição das diferenças identificadas ao nível molecular para o fenótipo melhorado da estirpe T1-E em termos de fermentação de lactose é aqui discutida. Em fermentações descontínuas com meio mineral, a nova estirpe T1-E consumiu rapidamente e por completo lactose em concentrações iniciais até 150 g•L-1. A concentração máxima de etanol atingida foi 8% (v/v) e a produtividade máxima foi 1.5 – 2 g•L-1•h-1. A estirpe T1-E foi também capaz de fermentar soro do queijo três vezes concentrado (cerca de 150 g•L-1 de lactose), produzindo 7% (v/v) de etanol. Estes resultados demonstram que a estirpe T1-E é a estirpe recombinante de S. cerevisiae mais eficiente para fermentação de lactose descrita na literatura. Sendo floculante, esta estirpe é adequada para desenvolver sistemas de fermentação de alta densidade celular que, quando operados em continuo com retenção da biomassa floculada, permitem atingir produtividades muito elevadas. O transporte de açúcares é um factor chave na determinação da eficiência de fermentação em ambos os processos estudados nesta tese. Estudos do transporte de lactose nas estirpes recombinantes de S. cerevisiae (T1 e T1-E) e em Kluyveromyces lactis revelaram que as taxas iniciais de transporte de lactose medidas pela metodologia padrão (i.e. usando suspensões de leveduras colhidas da fermentação, lavadas e guardadas em tampão sem nutrientes a baixa temperatura antes de serem utilizadas para ensaios com açúcar marcado radioactivamente) eram demasiado baixas (por factores de 3 a 8) para explicar as taxas de consumo de lactose observadas durante as fermentações. Uma breve incubação (1 – 7 min) com glucose (10 – 30 mM) aumentou a baixa EC e os baixos níveis de ATP intracelulares encontrados nas suspensões de leveduras guardadas sem nutrientes para os níveis encontrados em células de leveduras a fermentar activamente. Simultaneamente, essa incubação aumentou a actividade (Vmax) dos transportadores de lactose por factores de 1.5 a 5. Foram feitas observações semelhantes para o transporte de maltose em leveduras de cerveja. Estes resultados sugerem que o potencial electroquímico de protões responsável pelo transporte por mecanismos de simporte açúcar-protão é significativamente mais reduzido nas células guardadas em tampão sem nutrientes, utilizadas para os ensaios de transporte, do que nas células a fermentar activamente. Um breve tratamento das células guardadas sem nutrientes com glucose é sugerido como um método rápido para abordar de forma mais aproximada a capacidade dos sistemas de simporte açúcar-protão das leveduras a fermentar activamente.
Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/13463/2003.