Transcriptome reshaping of the evolved thermotolerant Saccharomyces cerevisiae strain compared with the parental strain by RNA-Seq

Elevated thermotolerance is an important desired property of Saccharomyces cerevisiae for its industrial applications. Here, adaptive laboratory evolution experiments were employed to further improve the thermotolerance of an industrial strain ScY. The resulting evolved strain showing enhanced thermotolerance was named ScY01. We sequenced mRNA from the cultures of the evolved strain ScY01 and the parental strain ScY grown on YP medium containing 200 g/l glucose at 40ºC at 200 rpm for 14 h ~ 16 h to the early-log phase. Differences in gene expression in ScY01 versus ScY revealed by RNA deep sequencing revealled that genes involved into glycolysis, amino acid biosynthesis and translation showed increased gene expressions, whereas mitochondrial translation and respiration associated genes showed decreased gene expressions. This suggested that the evolved strain might suppress its mitochondrial respiratory activity but boost its fermentation capacity, thereby providing enough ATP required for its more active energy-consuming pathways including amino acid and protein biosynthetic pathways.耐高温性提升是酿酒酵母（Saccharomyces cerevisiae）工业化应用中的关键优良目标性状。本研究借助适应性实验室进化（adaptive laboratory evolution）技术，对工业菌株ScY的耐高温性能进行进一步优化，最终获得的耐高温性显著增强的进化菌株被命名为ScY01。我们分别对进化菌株ScY01和亲本菌株ScY的培养物开展mRNA测序：两菌株均在含200g/L葡萄糖的YP培养基中，于40℃、200rpm条件下培养14~16小时至早期对数生长期。通过RNA深度测序（RNA deep sequencing）分析ScY01与ScY的基因表达差异，结果显示：参与糖酵解、氨基酸生物合成及翻译过程的基因表达显著上调，而线粒体翻译及呼吸相关基因的表达则显著下调。上述结果表明，该进化菌株可通过抑制线粒体呼吸活性、强化发酵能力，为氨基酸与蛋白质生物合成等更为活跃的耗能途径提供充足的ATP供给。