Inhibitor analysis and adaptive evolution of Saccharomyces cerevisiae for simultaneous saccharification and ethanol fermentation from industrial waste corncob residues

• High level of water-insoluble phenolics is responsible for poor fermentation of CCR.
• Evolutionary adaptation of Saccharomyces cerevisiae improved fermentability of CCR.
• High ethanol titer and productivity without pretreatment and detoxification of CCR.

Industrial waste corncob residues (CCR) are rich in cellulose and can be hydrolyzed directly without pretreatment. However, a poor fermentation performance was frequently observed in the simultaneous saccharification and ethanol fermentation (SSF) of CCR, although the furans and organic acid inhibitors were very low. In this study, the high level of water-insoluble phenolic compounds such as 2-furoic acid, ferulic acid, p-coumaric acid, guaiacol, and p-hydroxybenzoic acid were detected in CCR and inhibited the growth and metabolism of Saccharomyces cerevisiae DQ1. An evolutionary adaptation strategy was developed by culturing the S. cerevisiae DQ1 strain in a series of media with the gradual increase of CCR hydrolysate. The high ethanol concentration (62.68 g/L) and the yield (55.7%) were achieved in the SSF of CCR using the adapted S. cerevisiae DQ1. The results provided a practical method for improving performance of simultaneous saccharification and ethanol production from CCR.

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