Zhang Yi-Wen, Yang Jun-Jie, Qian Feng-Hui, Sutton Kate Brandon, Hjort Carsten, Wu Wen-Ping, Jiang Yu, Yang Sheng
Key Laboratory of Synthetic Biology, Center for Excellence of Molecular Plant Science, Chinese Academy of Sciences, Shanghai, China.
College of Life Science, University of Chinese Academy of Sciences, Beijing, China.
Nat Chem Biol. 2025 Mar;21(3):443-450. doi: 10.1038/s41589-024-01771-6. Epub 2024 Nov 4.
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对植物细胞壁进行化学预处理和酶水解产生的木质纤维素水解产物进行酵母发酵而生产的。在含有微生物抑制剂的水解产物中，木糖转化为乙醇是生物燃料生产中的一个主要瓶颈。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培育出一种过表达木糖分解代谢基因的酿酒酵母菌株。完全进化后的酵母菌株能够在工业规模上有效地将水解产物中的木糖转化为乙醇。我们阐明，木糖A、XKS1以及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中的突变，对于在含有高钠盐的玉米秸秆水解产物中有效利用木糖是有作用且足够的。我们培育的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，而且我们发现的遗传基础也有助于将该表型转移到生产乙醇以外化学品的酵母细胞工厂中。
