Enhanced xylose utilization in an adapted S. cerevisiae strain expressing xylose isomerase

We analyzed the genome sequence of an engineered S. cerevisiae strain expressing codon-optimized Prevotella ruminicola XI and XK genes that was previously adapted for increased xylose fermentation. Tetrad analysis of haploid spores from the heterozygous diploid showed that of the seven mutations present in the adapted strain, only pbs2L363X and pho13G208C mutations improved xylose utilization. Strains carrying a single mutated or deleted PBS2 or PHO13 did not show improved growth on xylose, indicating that both mutations were necessary. Double deletion of PBS2 and PHO13 also improved xylose utilization for strains expressing the XR/XDH pathway. However, unlike strains expressing the XI pathway, these strains also showed a significant improvement from deletion of the PHO13 gene alone.

本研究对表达经过密码子优化的Prevotella ruminicola XI和XK基因的工程化酿酒酵母菌株的基因组序列进行了分析。通过对杂合二倍体产生的单倍体孢子进行四分体分析，发现适应菌株中存在的七个突变中，仅有pbs2L363X和pho13G208C突变提高了木糖的利用率。携带单个突变或删除PBS2或PHO13的菌株在木糖上的生长并未得到改善，这表明这两个突变都是必要的。对于表达XR/XDH途径的菌株，PBS2和PHO13的双重删除也提高了木糖的利用率。然而，与表达XI途径的菌株不同，这些菌株在单独删除PHO13基因的情况下也显示出显著的改善。