PDF(Pubmed)
Abstract：
Major progress in developing Saccharomyces cerevisiae strains that utilize the pentose sugar xylose has been achieved. However, the high inhibitor content of lignocellulose hydrolysates still hinders efficient xylose fermentation, which remains a major obstacle for commercially viable second-generation bioethanol production. Further improvement of xylose utilization in inhibitor-rich lignocellulose hydrolysates remains highly challenging. In this work, we have developed a robust industrial S. cerevisiae strain able to efficiently ferment xylose in concentrated undetoxified lignocellulose hydrolysates. This was accomplished with novel multistep evolutionary engineering. First, a tetraploid strain was generated and evolved in xylose-enriched pretreated spruce biomass. The best evolved strain was sporulated to obtain a genetically diverse diploid population. The diploid strains were then screened in industrially relevant conditions. The best performing strain, MDS130, showed superior fermentation performance in three different lignocellulose hydrolysates. In concentrated corncob hydrolysate, with initial cell density of 1 g DW/l, at 35°C, MDS130 completely coconsumed glucose and xylose, producing ± 7% v/v ethanol with a yield of 91% of the maximum theoretical value and an overall productivity of 1.22 g/l/h. MDS130 has been developed from previous industrial yeast strains without applying external mutagenesis, minimizing the risk of negative side-effects on other commercially important properties and maximizing its potential for industrial application.
摘要：
开发利用戊糖木糖的酿酒酵母菌株已取得重大进展。然而,木质纤维素水解产物的高抑制剂含量仍然阻碍着木糖的高效发酵,这仍然是商业上可行的第二代生物乙醇生产的主要障碍。在富含抑制剂的木质纤维素水解产物中进一步改善木糖利用仍然是非常具有挑战性的。在这项工作中,我们开发了一种强大的工业酿酒酵母菌株，能够在浓缩的未脱毒的木质纤维素水解物中有效发酵木糖。这是通过新颖的多步骤进化工程完成的。首先,在富含木糖的预处理云杉生物量中产生并进化了四倍体菌株。最好的进化菌株被孢子化，以获得遗传多样性的二倍体种群。然后在工业相关条件下筛选二倍体菌株。表现最好的菌株，MDS130在三种不同的木质纤维素水解产物中显示出优越的发酵性能。在浓缩玉米芯水解物中，初始细胞密度为1gDW/L，在35°C,MDS130完全共同消耗葡萄糖和木糖，生产±7％v/v乙醇，收率为最大理论值的91％，总生产率为1.22g/L/h。MDS130是从以前的工业酵母菌株开发的，没有应用外部诱变，最大限度地减少对其他商业上重要的属性的负面副作用的风险，并最大限度地发挥其工业应用的潜力。
