Kinetic modeling and sensitivity analysis for higher ethanol production in self-cloning xylose-using Saccharomyces cerevisiae
We constructed a xylose-utilizing Saccharomyces cerevisiae strain using endogenous xylose-assimilating genes (strain K7-XYL). Such self-cloning yeast is expected to make a great contribution to cost reduction of ethanol production processes. However, it is difficult to modify self-cloning yeast for...
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Published in | Journal of bioscience and bioengineering Vol. 127; no. 5; pp. 563 - 569 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Japan
Elsevier B.V
01.05.2019
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Subjects | |
Online Access | Get full text |
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Summary: | We constructed a xylose-utilizing Saccharomyces cerevisiae strain using endogenous xylose-assimilating genes (strain K7-XYL). Such self-cloning yeast is expected to make a great contribution to cost reduction of ethanol production processes. However, it is difficult to modify self-cloning yeast for optimal performance because the available gene source is limited. To improve the ethanol productivity of our self-cloning yeast, a kinetic model of ethanol production was constructed and sensitivity analysis was performed. Alcohol dehydrogenase (ADH1) was identified as a metabolic bottleneck reaction in the ethanol production pathway. An ADH1 overexpression strain (K7-XYL-ADH1) was constructed and evaluated in YP (yeast extract 10 g/L, peptone 20 g/L) medium containing 50 g/L xylose as the sole carbon source. Strain K7-XYL-ADH1 showed higher ethanol productivity (13.8 g/L) than strain K7-XYL (12.5 g/L). Then, K7-XYL-ADH1 was evaluated in YP medium containing 80 g/L glucose and 50 g/L xylose; however, the ethanol productivity did not change relative to that of K7-XYL (K7-XYL 46.3 g/L, K7-XYL-ADH1 45.9 g/L). We presumed that due to the presence of glucose, the internal redox balance of the cells had changed. On culturing in an aerated 5-L jar fermentor to change the internal redox balance of cells, strain K7-XYL-ADH1 showed higher ethanol productivity than K7-XYL (K7-XYL 45.0 g/L, K7-XYL-ADH1 49.4 g/L). Our results confirmed that ADH1 was a metabolic bottleneck in the ethanol production pathway. By eliminating the bottleneck, self-cloning yeast showed almost the same ethanol productivity as genetically modified yeast. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1389-1723 1347-4421 |
DOI: | 10.1016/j.jbiosc.2018.10.020 |