Effects of glucose fluctuations on synchrony in fed-batch fermentation of Saccharomyces cerevisiae

1992 ◽  
Vol 8 (6) ◽  
pp. 501-507 ◽  
Author(s):  
Pradyumna K. Namdev ◽  
B. G. Thompson ◽  
Dennis B. Ward ◽  
Murray R. Gray
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Batch Fermentation ◽  
Fed Batch ◽  
Fed Batch Fermentation ◽  
Glucose Fluctuations

scholarly journals Efficient Alcoholic Conversion of Glycerol by Engineered Saccharomyces cerevisiae

2021 ◽  
Author(s):  
Takashi Watanabe ◽  
Sadat M. R. Khattab
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nicotinamide Adenine Dinucleotide ◽  
Batch Fermentation ◽  
Plant Biomass ◽  
Glycerol Oxidation ◽  
Fed Batch ◽  
Fed Batch Fermentation ◽  
Engineered Saccharomyces Cerevisiae ◽  
Biomass Decomposition ◽  
Engineered Strain

Glycerol is an eco-friendly solvent that enhances plant biomass decomposition via glycerolysis in many pretreatment methods. Nonetheless, the lack of efficient conversion of glycerol by natural Saccharomyces cerevisiae hinders its use in these methods. Here, we have aimed to develop a complete strategy for the generation of efficient glycerol-converting yeast by modifying the oxidation of cytosolic nicotinamide adenine dinucleotide (NADH) by an O2-dependent dynamic shuttle, while abolishing both glycerol phosphorylation and biosynthesis. By following a vigorous glycerol oxidation pathway, the engineered strain increased the conversion efficiency (CE) to up to 0.49 g ethanol/g glycerol (98% of theoretical CE), with production rate > 1 g×L×h, when glycerol was supplemented in a single fed-batch fermentation in a rich medium. Furthermore, the engineered strain fermented a mixture of glycerol and glucose, producing > 86 g/L bioethanol with 92.8% CE. To our knowledge, this is the highest ever reported titer in this field. Notably, this strategy changed conventional yeast from a non-grower on minimal medium containing glycerol to a fermenting strain with productivity of 0.25-0.5 g×L×h and 84-78% CE, which converted 90% of the substrate to products. Our findings may improve the utilization of glycerol in several eco-friendly biorefinery approaches.

Sugarcane must fed-batch fermentation by Saccharomyces cerevisiae: impact of sterilized and non-sterilized sugarcane must

2019 ◽  
Vol 112 (8) ◽  
pp. 1177-1187
Author(s):  
Maria Letícia Bonatelli ◽  
Jaciane Lutz Ienczak ◽  
Carlos Alberto Labate
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Batch Fermentation ◽  
Fed Batch ◽  
Fed Batch Fermentation

scholarly journals Improving xylitol yield by deletion of endogenous xylitol-assimilating genes: a study of industrial Saccharomyces cerevisiae in fermentation of glucose and xylose

2020 ◽  
Vol 20 (8) ◽  
Author(s):  
Bai-Xue Yang ◽  
Cai-Yun Xie ◽  
Zi-Yuan Xia ◽  
Ya-Jing Wu ◽  
Min Gou ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Batch Fermentation ◽  
Xylose Reductase ◽  
Fed Batch ◽  
Fed Batch Fermentation ◽  
Engineered Saccharomyces Cerevisiae ◽  
Sorbitol Dehydrogenases ◽  
Simultaneous Saccharification ◽  
Xylitol Yield ◽  
Endogenous Enzymes

ABSTRACT Engineered Saccharomyces cerevisiae can reduce xylose to xylitol. However, in S.cerevisiae, there are several endogenous enzymes including xylitol dehydrogenase encoded by XYL2, sorbitol dehydrogenases encoded by SOR1/SOR2 and xylulokinase encoded by XKS1 may lead to the assimilation of xylitol. In this study, to increase xylitol accumulation, these genes were separately deleted through CRISPR/Cas9 system. Their effects on xylitol yield of an industrial S. cerevisiae CK17 overexpressing Candida tropicalis XYL1 (encoding xylose reductase) were investigated. Deletion of SOR1/SOR2 or XKS1 increased the xylitol yield in both batch and fed-batch fermentation with different concentrations of glucose and xylose. The analysis of the transcription level of key genes in the mutants during fed-batch fermentation suggests that SOR1/SOR2 are more crucially responsible for xylitol oxidation than XYL2 under the genetic background of S.cerevisiae CK17. The deletion of XKS1 gene could also weaken SOR1/SOR2 expression, thereby increasing the xylitol accumulation. The XKS1-deleted strain CK17ΔXKS1 produced 46.17 g/L of xylitol and reached a xylitol yield of 0.92 g/g during simultaneous saccharification and fermentation (SSF) of pretreated corn stover slurry. Therefore, the deletion of XKS1 gene provides a promising strategy to meet the industrial demands for xylitol production from lignocellulosic biomass.

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