Reasons for 2-furaldehyde and 5-hydroxymethyl-2-furaldehyde resistance in Saccharomyces cerevisiae: current state of knowledge and perspectives for further improvements

Authors: Liu, Zonglin

Submitted to: Applied Microbiology and Biotechnology
Publication Type: Review Article
Publication Acceptance Date: 3/23/2021
Publication Date: 4/8/2021
Citation: Liu, Z. 2021. Reasons for 2-furaldehyde and 5-hydroxymethyl-2-furaldehyde resistance in Saccharomyces cerevisiae: current state of knowledge and perspectives for further improvements. Applied Microbiology and Biotechnology. 105:2991–3007. https://doi.org/10.1007/s00253-021-11256-4.
DOI: https://doi.org/10.1007/s00253-021-11256-4

Interpretive Summary: Toxic chemicals are commonly generated as byproducts during decomposition of fibrous biomass used for production of renewable fuels and chemicals. The byproducts interfere with microbial growth and fermentation. In this research, an ARS scientist used time-course studies to distinguish a genuine adapted resistance to inhibitors from innate stress response in yeast for the first time. Resistance characteristics were found in numerous cellular pathways, and uncertainties in literature were distilled to direct future research. Understanding mechanisms for yeast resistance aids development of next-generation biocatalysts, which is a desired means to overcome the toxicity that hampers biomass conversion. This research will benefit development of research strategies for economic conversion of biomass to fuels and chemicals.

Technical Abstract: Common toxic compounds 2-furaldehyde (furfural) and 5-hydroxymethyl-2-furaldehyde (HMF) are formed from dehydration of pentose and hexose, respectively, during decomposition of lignocellulosic biomass polymers. Furfural and HMF represent a major class of aldehyde toxic chemicals that inhibit microbial growth and interfere with subsequent fermentation for production of renewable fuels and chemicals. Understanding mechanisms of yeast tolerance aids development of tolerant strains as the most economic means to overcome the toxicity. This review updates current knowledge on yeast resistance to these toxic chemicals obtained from rapid advances in the past few years. Findings are largely exemplified by an adapted strain of Saccharomyces cerevisiae NRRL Y-50049 compared with its progenitor, the industrial type strain NRRL Y-12632. Newly characterized molecular phenotypes distinguished acquired resistant components of Y-50049 from innate stress response of its progenitor Y-12632. These findings also raised important questions on how to address more deeply ingrained changes in addition to local renovations for yeast adaptation. An early review on understandings of yeast tolerance to these inhibitory compounds is available and its contents omitted here to avoid redundancy. Controversial and confusing issues on identification of yeast resistance to furfural and HMF are further clarified aiming improved future research. Propositions and perspectives on research understanding molecular mechanisms of yeast resistance and future improvements are also presented.