Transgenic Saccharomyces cerevisiae Exhibits Enhanced Fermentation at High Temperatures

High temperature inhibits cell growth and ethanol fermentation of Saccharomyces cerevisiae. Previous studies, however, have found that overexpression of stress-related transcription factor genes in yeasts can improve the stress tolerance of the hosts. To increase ethanol yield of high-temperature fermentation, the team of Pengsong Li and Xiaofen Fu from Tsinghua University in China developed a series of S. cerevisiae strains by expressing eight transcription factor genes from S. cerevisiae and seven transcription factor genes from the thermotolerant Kluyveromyces marxianus in S. cerevisiae.

Their results showed that the KmHsf1 and KmMsn2 TF genes can enhance cell growth of S. cerevisiae at 40–42°C. Batch fermentation results at 43°C that the KmHSF1 and KmMSN2-expressing strains could reach a significantly higher ethanol concentrations compared to the control strain.

Analysis found that the expression of KmHSF1 and KmMSN2 resulted in 55 and 50 differently expressed genes, respectively. Further analysis revealed that KmHsf1 could increase ethanol production by regulating genes related to transporter activity while KmMsn2 could promote ethanol fermentation by regulating genes associated with glucose metabolic process. In addition, KmMsn2 may also help to cope with high temperature by regulating genes associated with lipid metabolism.