Ergosterol supplementation improves furfural tolerance of Saccharomyces cerevisiae to produce ethanol and its underlying mechanism

Abstract

Furfural produced during lignocellulose pretreatment to reduce the recalcitrance inhibits the growth of Saccharomyces cerevisiae and reduces ethanol yield. To reduce the adverse effect of furfural on S. cerevisiae, exogenous ergosterol was supplemented and the impact on S. cerevisiae under furfural stress was studied. The lag phage was shortened by 50%, and the maximum ethanol yield was increased by 158% with 50 mg/L ergosterol supplementation under 4 g/L furfural stress. Flow cytometry analysis results showed that permeable cells and intracellular reactive oxygen species were decreased by 45 and 53%, respectively with the addition of ergosterol under furfural stress. The fatty acid composition of S. cerevisiae was changed; the intracellular glycerol and ergosterol content was increased after ergosterol supplementation. The saturation of fatty acid was increased. Addition of ergosterol promoted cell growth by decreasing oxidative stress. Under 4 g/L furfural stress, the lag phage of S. cerevisiae BY4741 (erg3△) and S. cerevisiae BY4741 (erg5△) was longer than that of S. cerevisiae BY4741, and the maximum ethanol concentration was decreased.