Lignocellulosic ethanol is produced by yeast fermentation of lignocellulosic hydrolysates generated by chemical pretreatment and enzymatic hydrolysis of plant cell walls. The conversion of xylose into ethanol in hydrolysates containing microbial inhibitors is a major bottleneck in biofuel production. We identified sodium salts as the primary yeast inhibitors, and evolved a Saccharomyces cerevisiae strain overexpressing xylose catabolism genes in xylose or glucose-mixed medium containing sodium salts. The fully evolved yeast strain can efficiently convert xylose in the hydrolysates to ethanol on an industrial scale. We elucidated that the amplification of xylA, XKS1 and pentose phosphate pathway-related genes TAL1, RPE1, TKL1, RKI1, along with mutations in NFS1, TRK1, SSK1, PUF2 and IRA1, are responsible and sufficient for the effective xylose utilization in corn stover hydrolysates containing high sodium salts. Our evolved or reverse-engineered yeast strains enable industrial-scale production of lignocellulosic ethanol and the genetic foundation we uncovered can also facilitate transfer of the phenotype to yeast cell factories producing chemicals beyond ethanol.

木质纤维素乙醇是通过化学预处理和植物细胞壁酶解产生的木质纤维素水解物的酵母发酵生产的。在含有微生物抑制剂的水解产物中将木糖转化为乙醇是生物燃料生产的主要瓶颈。我们确定钠盐是主要的酵母抑制剂，并在含有钠盐的木糖或葡萄糖混合培养基中进化出过表达木糖分解代谢基因的酿酒酵母菌株。完全进化的酵母菌株可以有效地将水解产物中的木糖以工业规模转化为乙醇。我们阐明了 xylA 、 XKS1 和磷酸戊糖途径相关基因 TAL1 、 RPE1 、 TKL1 、 RKI1 的扩增，以及 NFS1 、 TRK1 、 SSK1 、 PUF2 和 IRA1 的突变，是木糖在含有高钠盐的水解物中有效利用的原因和充分的。我们进化或逆向工程的酵母菌株能够实现木质纤维素乙醇的工业规模生产，我们发现的遗传基础还可以促进表型转移到生产乙醇以外的化学物质的酵母细胞工厂。