Effect of Low-concentration Furfural on Sulfur Amino Acid Biosynthesis in Saccharomyces cerevisiae

Ethanol produced from lignocellulosic biomass (bioethanol) is a promising alternative fuel to gasoline. Production of bioethanol from lignocellulose requires various steps, including pretreatment, enzymatic hydrolysis and fermentation. However, many fermentation inhibitors, including furfural and 5-hydroxymethyl furfural, are generated during the hydrothermal pretreatment of lignocellulose. Recent studies have identified techniques for removing fermentation inhibitors from lignocellulosic hydrolysate. The present study focused on the effect of low-concentration furfural on ethanol production by Saccharomyces cerevisiae . Specifically, gene expression of furfural-inducible genes was analyzed using a S. cerevisiae DNA microarray. The expression of most sulfur amino acid biosynthesis genes increased in response to furfural. To determine whether furfural induces the depletion of sulfur-containing amino acids, the effect of the addition of methionine on yeast growth was investigated. However, exogenous addition of methionine did not compensate for the inhibitory effect. The findings of this study show that furfural affects amino acid synthesis, even at low concentrations, and may be important in the development of high-efficiency processes for large-scale bioethanol production from lignocellulosic biomass.