Physiological and Metabolomic Analysis of Issatchenkia orientalis MTY1 With Multiple Tolerance for Cellulosic Bioethanol Production

Yeast with multiple tolerance onto harsh conditions has a number of advantages for bioethanol production. In this study, an alcohol yeast of Issatchenkia orientalis MTY1 is isolated in a Korean winery and its multiple tolerance against high temperature and acidic conditions is characterized in microaerobic batch cultures and by metabolomic analysis. In a series of batch cultures using 100gL^-1 glucose, I. orientalis MTY1 possesses wider growth ranges at pH 2-8 and 30-45°C than a conventional yeast of Saccharomyces cerevisiae D452-2. Moreover, I. orientalis MTY1 showes higher cell growth and ethanol productivity in the presence of acetic acid or furfural than S. cerevisiae D452-2. I. orientalis MTY1 produces 41.4gL^-1 ethanol with 1.5gL^-1h^-1 productivity at 42°C and pH 4.2 in the presence of 4gL^-1 acetic acid, whereas a thermo-tolerant yeast of Kluyvermyces marxianus ATCC36907 does not grow. By metabolomics by GC-TOF MS and statistical analysis of 125 metabolite peaks, it is revealed that the thermo-tolerance of I. orientalis MTY1 might be ascribed to higher contents of unsaturated fatty acids, purines and pyrimidines than S. cerevisiae D452-2. Conclusively, I. orientalis MTY1 could be a potent workhorse with multiple tolerance against harsh conditions considered in cellulosic bioethanol production.