Metabolic engineering of Saccharomyces cerevisiae for second-generation ethanol production from xylo-oligosaccharides and acetate

Dielle Pierotti Procópio, Jae Won Lee, Jonghyeok Shin, Robson Tramontina, Patrícia Felix Ávila, Lívia Beatriz Brenelli, Fabio Márcio Squina, André Damasio, Sarita Cândida Rabelo, Rosana Goldbeck, Telma Teixeira Franco, David Leak, Yong Su Jin, Thiago Olitta Basso

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2 Citations (SciVal)

Abstract

Simultaneous intracellular depolymerization of xylo-oligosaccharides (XOS) and acetate fermentation by engineered Saccharomyces cerevisiae offers significant potential for more cost-effective second-generation (2G) ethanol production. In the present work, the previously engineered S. cerevisiae strain, SR8A6S3, expressing enzymes for xylose assimilation along with an optimized route for acetate reduction, was used as the host for expressing two β-xylosidases, GH43-2 and GH43-7, and a xylodextrin transporter, CDT-2, from Neurospora crassa, yielding the engineered SR8A6S3-CDT-2-GH34-2/7 strain. Both β-xylosidases and the transporter were introduced by replacing two endogenous genes, GRE3 and SOR1, that encode aldose reductase and sorbitol (xylitol) dehydrogenase, respectively, and catalyse steps in xylitol production. The engineered strain, SR8A6S3-CDT-2-GH34-2/7 (sor1Δ gre3Δ), produced ethanol through simultaneous XOS, xylose, and acetate co-utilization. The mutant strain produced 60% more ethanol and 12% less xylitol than the control strain when a hemicellulosic hydrolysate was used as a mono- and oligosaccharide source. Similarly, the ethanol yield was 84% higher for the engineered strain using hydrolysed xylan, compared with the parental strain. Xylan, a common polysaccharide in lignocellulosic residues, enables recombinant strains to outcompete contaminants in fermentation tanks, as XOS transport and breakdown occur intracellularly. Furthermore, acetic acid is a ubiquitous toxic component in lignocellulosic hydrolysates, deriving from hemicellulose and lignin breakdown. Therefore, the consumption of XOS, xylose, and acetate expands the capabilities of S. cerevisiae for utilization of all of the carbohydrate in lignocellulose, potentially increasing the efficiency of 2G biofuel production.

Original languageEnglish
Article number19182
JournalScientific Reports
Volume13
Issue number1
Early online date6 Nov 2023
DOIs
Publication statusPublished - 6 Nov 2023

Bibliographical note

Funding Information:
This work was supported by the São Paulo Research Foundation (FAPESP) [grant numbers #2015/50590-4, #2015/50612-8, #2017/15477-8, #2018/17172-2, #2018/01759-4, #2019/18075-3, #2020/05784-3, #2021/04254-3, #2022/05731-2 and #2022/08958-8] and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) [grant numbers 306279/2020-7 (FMS) and 304294/2022-5 (TOB)].

Funding Information:
We would like to thank The Brazilian Biorenewables National Laboratory (LNBR/CNPEM/MCTIC) for infrastructure.

ASJC Scopus subject areas

  • General

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