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Enhanced direct ethanol production by cofactor optimization of cell surface-displayed xylose isomerase in yeast.
- Source :
- Biotechnology Progress; Jul/Aug2017, Vol. 33 Issue 4, p1068-1076, 9p
- Publication Year :
- 2017
-
Abstract
- Xylose isomerase (XylC) from Clostridium cellulovorans can simultaneously perform isomerization and fermentation of d-xylose, the main component of lignocellulosic biomass, and is an attractive candidate enzyme. In this study, we optimized a specified metal cation in a previously established Saccharomyces cerevisiae strain displaying XylC. We investigated the effect of each metal cation on the catalytic function of the XylC-displaying S. cerevisiae. Results showed that the divalent cobalt cations (Co<superscript>2+</superscript>) especially enhanced the activity by 46-fold. Co<superscript>2+</superscript> also contributed to d-xylose fermentation, which resulted in improving ethanol yields and xylose consumption rates by 6.0- and 2.7-fold, respectively. Utility of the extracellular xylose isomerization system was exhibited in the presence of mixed sugar. XylC-displaying yeast showed the faster d-xylose uptake than the yeast producing XI intracellularly. Furthermore, direct xylan saccharification and fermentation was performed by unique yeast co-culture system. A xylan-degrading yeast strain was established by displaying two kinds of xylanases; endo-1,4-β-xylanase (Xyn11B) from Saccharophagus degradans, and β-xylosidase (XlnD) from Aspergillus niger. The yeast co-culture system enabled fine-tuning of the initial ratios of the displayed enzymes (Xyn11B:XlnD:XylC) by adjusting the inoculation ratios of Xylanases (Xyn11B and XlnD)-displaying yeast and XylC-displaying yeast. When the enzymes were inoculated at the ratio of 1:1:2 (1.39 × 10<superscript>13</superscript>: 1.39 × 10<superscript>13</superscript>: 2.78 × 10<superscript>13</superscript> molecules), 6.0 g/L ethanol was produced from xylan. Thus, the cofactor optimization and the yeast co-culture system developed in this study could expand the prospect of biofuels production from lignocellulosic biomass. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1068-1076, 2017 [ABSTRACT FROM AUTHOR]
- Subjects :
- ETHANOL
ALCOHOLS (Chemical class)
TATP (Chemical)
CELL membranes
XYLOSE
YEAST
Subjects
Details
- Language :
- English
- ISSN :
- 87567938
- Volume :
- 33
- Issue :
- 4
- Database :
- Complementary Index
- Journal :
- Biotechnology Progress
- Publication Type :
- Academic Journal
- Accession number :
- 124767138
- Full Text :
- https://doi.org/10.1002/btpr.2478