Xylose Fermentation by Saccharomyces cerevisiae: Challenges and Prospects

Being a microbial host for lignocellulosic biofuel production, Saccharomyces cerevisiae needs to be engineered to express a heterologous xylose pathway; however, it has been challenging to optimize the engineered strain for efficient and rapid fermentation of xylose. Deletion of PHO13 (Δpho13) has been reported to be a crucial genetic perturbation in improving xylose fermentation. A confirmed mechanism of the Δpho13 effect on xylose fermentation is that the Δpho13 transcriptionally activates the genes in the non-oxidative pentose phosphate pathway (PPP). In the current study, we found a couple of engineered strains, of which phenotypes were not affected by Δpho13 (Δpho13-negative), among many others we examined. Genome resequencing of the Δpho13-negative strains revealed that a loss-of-function mutation in GCR2 was responsible for the phenotype. Gcr2 is a global transcriptional factor involved in glucose metabolism. The results of RNA-seq confirmed that the deletion of GCR2 (Δgcr2) led to the upregulation of PPP genes as well as downregulation of glycolytic genes, and changes were more significant under xylose conditions than those under glucose conditions. Although there was no synergistic effect between Δpho13 and Δgcr2 in improving xylose fermentation, these results suggested that GCR2 is a novel knockout target in improving lignocellulosic ethanol production.

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The response mechanisms of industrial Saccharomyces cerevisiae to acetic acid and formic acid during mixed glucose and xylose fermentation

Process Biochemistry ◽

10.1016/j.procbio.2020.01.002 ◽

2020 ◽

Vol 91 ◽

pp. 319-329

Author(s):

Bo Li ◽

Cai-Yun Xie ◽

Bai-Xue Yang ◽

Min Gou ◽

Zi-Yuan Xia ◽

...

Keyword(s):

Saccharomyces Cerevisiae ◽

Acetic Acid ◽

Formic Acid ◽

Xylose Fermentation ◽

Glucose And Xylose Fermentation

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Long-term incomplete xylose fermentation, after glucose exhaustion, with Candida shehatae co-immobilized with Saccharomyces cerevisiae

Microbiological Research ◽

10.1016/j.micres.2006.07.005 ◽

2007 ◽

Vol 162 (3) ◽

pp. 211-218 ◽

Cited By ~ 17

Author(s):

T. Lebeau ◽

T. Jouenne ◽

G.-A. Junter

Keyword(s):

Saccharomyces Cerevisiae ◽

Xylose Fermentation ◽

Candida Shehatae

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gTME for Improved Xylose Fermentation of Saccharomyces cerevisiae

Applied Biochemistry and Biotechnology ◽

10.1007/s12010-008-8431-9 ◽

2008 ◽

Vol 160 (2) ◽

pp. 574-582 ◽

Cited By ~ 37

Author(s):

Hongmei Liu ◽

Ming Yan ◽

Cangang Lai ◽

Lin Xu ◽

Pingkai Ouyang

Keyword(s):

Saccharomyces Cerevisiae ◽

Xylose Fermentation

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Functional Expression of a Bacterial Xylose Isomerase in Saccharomyces cerevisiae

Applied and Environmental Microbiology ◽

10.1128/aem.02522-08 ◽

2009 ◽

Vol 75 (8) ◽

pp. 2304-2311 ◽

Cited By ~ 174

Author(s):

Dawid Brat ◽

Eckhard Boles ◽

Beate Wiedemann

Keyword(s):

Saccharomyces Cerevisiae ◽

Heterologous Expression ◽

Xylose Fermentation ◽

Thermus Thermophilus ◽

Xylose Isomerase ◽

Functional Expression ◽

Yeast Cells ◽

Highly Active ◽

Excellent Starting Point ◽

Starting Point

ABSTRACT In industrial fermentation processes, the yeast Saccharomyces cerevisiae is commonly used for ethanol production. However, it lacks the ability to ferment pentose sugars like d-xylose and l-arabinose. Heterologous expression of a xylose isomerase (XI) would enable yeast cells to metabolize xylose. However, many attempts to express a prokaryotic XI with high activity in S. cerevisiae have failed so far. We have screened nucleic acid databases for sequences encoding putative XIs and finally were able to clone and successfully express a highly active new kind of XI from the anaerobic bacterium Clostridium phytofermentans in S. cerevisiae. Heterologous expression of this enzyme confers on the yeast cells the ability to metabolize d-xylose and to use it as the sole carbon and energy source. The new enzyme has low sequence similarities to the XIs from Piromyces sp. strain E2 and Thermus thermophilus, which were the only two XIs previously functionally expressed in S. cerevisiae. The activity and kinetic parameters of the new enzyme are comparable to those of the Piromyces XI. Importantly, the new enzyme is far less inhibited by xylitol, which accrues as a side product during xylose fermentation. Furthermore, expression of the gene could be improved by adapting its codon usage to that of the highly expressed glycolytic genes of S. cerevisiae. Expression of the bacterial XI in an industrially employed yeast strain enabled it to grow on xylose and to ferment xylose to ethanol. Thus, our findings provide an excellent starting point for further improvement of xylose fermentation in industrial yeast strains.

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Quantitatively understanding reduced xylose fermentation performance in AFEXTM treated corn stover hydrolysate using Saccharomyces cerevisiae 424A (LNH-ST) and Escherichia coli KO11

Bioresource Technology ◽

10.1016/j.biortech.2012.01.154 ◽

2012 ◽

Vol 111 ◽

pp. 294-300 ◽

Cited By ~ 33

Author(s):

Mingjie Jin ◽

Venkatesh Balan ◽

Christa Gunawan ◽

Bruce E. Dale

Keyword(s):

Escherichia Coli ◽

Saccharomyces Cerevisiae ◽

Corn Stover ◽

Xylose Fermentation ◽

Fermentation Performance ◽

Escherichia Coli Ko11 ◽

Corn Stover Hydrolysate

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Decreased Xylitol Formation during Xylose Fermentation in Saccharomyces cerevisiae Due to Overexpression of Water-Forming NADH Oxidase

Applied and Environmental Microbiology ◽

10.1128/aem.06635-11 ◽

2011 ◽

Vol 78 (4) ◽

pp. 1081-1086 ◽

Cited By ~ 34

Author(s):

Guo-Chang Zhang ◽

Jing-Jing Liu ◽

Wen-Tao Ding

Keyword(s):

Saccharomyces Cerevisiae ◽

Xylose Fermentation ◽

Nadh Oxidase ◽

Xylose Reductase ◽

Control Strain ◽

Content Type ◽

Ethanol Yields ◽

Glycerol Yield ◽

Set Up ◽

And Control

ABSTRACTThe recombinant xylose-fermentingSaccharomyces cerevisiaestrain harboring xylose reductase (XR) and xylitol dehydrogenase (XDH) fromScheffersomyces stipitisrequires NADPH and NAD+, creates cofactor imbalance, and causes xylitol accumulation during growth ond-xylose. To solve this problem,noxE, encoding a water-forming NADH oxidase fromLactococcus lactisdriven by thePGK1promoter, was introduced into the xylose-utilizing yeast strain KAM-3X. A cofactor microcycle was set up between the utilization of NAD+by XDH and the formation of NAD+by water-forming NADH oxidase. Overexpression ofnoxEsignificantly decreased xylitol formation and increased final ethanol production during xylose fermentation. Under xylose fermentation conditions with an initiald-xylose concentration of 50 g/liter, the xylitol yields for of KAM-3X(pPGK1-noxE) and control strain KAM-3X were 0.058 g/g xylose and 0.191 g/g, respectively, which showed a 69.63% decrease owing tonoxEoverexpression; the ethanol yields were 0.294 g/g for KAM-3X(pPGK1-noxE) and 0.211 g/g for the control strain KAM-3X, which indicated a 39.33% increase due tonoxEoverexpression. At the same time, the glycerol yield also was reduced by 53.85% on account of the decrease in the NADH pool caused by overexpression ofnoxE.

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