초록
<P><B>Abstract</B></P> <P>Furfural is a major toxic byproduct present in the hydrolysate of lignocellulosic biomass, which inhibits the growth and ethanol fermentation of <I>Saccharomyces cerevisiae</I>. To enhance yeast tolerance to furfural, extracellular redox potential (ORP) regulation was employed for the fermentation system through controlling ORP at −150 mV, −100 mV and −50 mV, respectively, by adjusting its aeration. When ORP was controlled at −100 mV, yeast cells exhibited improved growth, furfural degradation and ethanol production. Analysis of intracellular redox pairs such as NADH/NAD<SUP>+</SUP> and GSH/GSSG indicated a correlation between extracellular ORP and intracellular redox homeostasis. Moreover, intracellular reactive oxygen species (ROS) caused by furfural stress decreased under the redox control condition, which consequently conferred yeast cells tolerance to furfural. Comparative transcriptome analysis for yeast cells sampling under the ORP control at −100 mV further revealed that the expression of genes for proliferation was up-regulated to degrade furfural more efficiently. These results demonstrated that extracellular ORP regulation would be a strategy for enhancing yeast tolerance to furfural stress during cellulosic ethanol fermentation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Controlling extracellular redox potential enhances the tolerance of yeast to furfural. </LI> <LI> Intracellular redox status shows a tight correlation with extracellular redox potential. </LI> <LI> −100 mV is an optimal redox level to obtain high biomass and ethanol titer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>