Adaptation of the industrial yeast Saccharomyces cerevisiae against toxic chemicals for lignocellulose-to-biofuels conversion

Authors: Liu, Zonglin

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/10/2019
Publication Date: 4/20/2020
Citation: Liu, Z. 2020. Adaptation of the industrial yeast Saccharomyces cerevisiae against toxic chemicals for lignocellulose-to-biofuels conversion . TAGC 2020, The Allied Genetics conference April 22-26, 2020, Gaylord National Resort & Convention Center, National Harbor, Metro Washington, DC. [abstract] 2020-04-20T20:30:50Z.

Interpretive Summary:

Technical Abstract: The industrial yeast Saccharomyces cerevisiae is a workhorse widely applied in fermentation-based industrial applications. It has a plastic genome and great flexibility in adaptation to varied environmental conditions. A tolerant strain of NRRL Y-50049 was successfully obtained by environmental evolution from a progenitor of industrial type strain NRRL Y-12632. Strain Y-50049 can in situ detoxify 2-furaldehyde (furfural) and 5-hydroxymethyl-2-furaldehyde (HMF), major toxic chemicals derived from lignocellulose-to-fuels conversion, while producing ethanol. Based on characterizations of a novel aldehyde reductase gene (ARI1) and its protein, a mode of action was established for conversion of furfural and HMF into non-harmful furanmethanol (FM) and furandimethanol (FDM), respectively. By analyzing comparative transcriptome and protein expression profile time courses, glucose-6-phosphate (Zwf1) in Y-50049 was found as the key protein to driving the glucose metabolism toward the oxidative branch of the pentose phosphate pathway, facilitating in situ detoxification. These results suggested a fine-tuned mechanism of the reprogrammed detoxification pathway in Y-50049. The activated expression of Zwf1 appeared to generate essential cofactor NADPH to enable reduction of furaldehydes through a group of aldehyde reduction enzymes. In return, the active aldehyde reductions released desirable feedbacks of NADP+ stimulating continued oxidative activity of Zwf1. Thus, a well-maintained cofactor regeneration cycle was restored overcoming the furfural-HMF stress. Key transcription factor genes involved in major altered pathways were also identified. Furthermore, numerous pathway-based tolerant phenotypes of Y-50049 were highlighted that distinguished the tolerance components from the innate stress response of its progenitor. Identification of legitimate tolerance phenotypes is critical for continued investigations in dissection of mechanisms of yeast tolerance. Knowledge and insight obtained by this research aid understanding yeast adaptation at the genomic level and development of the next-generation biocatalyst for advanced biofuels production from lignocellulosic materials.