Identification of glycolaldehyde as the key inhibitor of bioethanol fermentation by yeast and genome-wide analysis of its toxicity
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Degradation of lignocellulose with pressurised hot water is an efficient method of bioethanol production. However, the resultant solution inhibits ethanol fermentation by Saccharomyces cerevisiae. Here, we first report that glycolaldehyde, which is formed when lignocellulose is treated with pressurised hot water, inhibits ethanol fermentation. The final concentration of glycolaldehyde formed by the treatment of lignocellulose with pressurised hot water ranges from 1 to 24 mM, and 1–10 mM glycolaldehyde was sufficient to inhibit fermentation. This result indicates that glycolaldehyde is one of the main substances responsible for inhibiting fermentation after pressurised hot water degradation of lignocellulose. Genome-wide screening of S. cerevisiae revealed that genes encoding alcohol dehydrogenase, methylglyoxal reductase, polysomes, and the ubiquitin ligase complex are required for glycolaldehyde tolerance. These novel findings will provide new perspectives on breeding yeast for bioethanol production from biomass treated with pressurised hot water.
KeywordsBioethanol Glycolaldehyde Yeast Lignocellulose Genome
Synthetic complete medium
Complete supplement mixture
Standard error of the mean
NH first discovered the inhibitory effect of glycolaldehyde on yeast fermentation. HK designed and supervised the whole research. LNJ performed most of the experiments. HK wrote the manuscript.
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