Comparative metabolite profiling of wild type and thermo-tolerant mutant of Saccharomyces cerevisiae

Simultaneous saccharification and fermentation (SSF) is a process of enzymatic saccharification and yeast fermentation used for producing lignocellulosic ethanol, and is performed at high temperature for effective enzymatic saccharification. Thermo-tolerant yeast is needed for high ethanol yield from yeast fermentation. A thermo-tolerant mutant yeast, SSK2, derived from Saccharomyces cerevisiae BY4741, has been generated previously. However, the thermo-tolerance mechanisms in SSK2 remain unclear. In this study, to investigate the change of metabolisms in thermo-tolerant mutant, metabolomics was performed based on gas chromatography/time-of-flight mass spectrometry (GC/TOF MS). In total, 91 intracellular metabolites were identified by GC/TOF MS; the metabolite profiles of BY4741 and SSK2, cultivated at 30 °C and 42 °C, were clearly discriminated by principal component analysis (PCA) and hierarchical clustering analysis (HCA). The metabolomics results indicated that the metabolism of amino acids, cell wall and membrane, and fatty acids were changed by heat stress and were key factors in yeast thermo-tolerance. In this study, metabolomics was successfully exploited to reveal the changes of metabolisms in the thermo-tolerant yeast, and these metabolic changes could be used as the clues for future development of thermo-tolerant yeasts.