Ishchuk O. Molecular mechanisms of resistance to high-temperatures and ethanol in non-conventional yeasts

Object of research: mechanisms of thermo- and ethanol-resistance in non-conventional yeasts. The aim of the work: identification of genes conferring high-temperature tolerance and ethanol resistance in non-conventional yeasts Hansenula polymorpha and Dekkera bruxellensis on the basis of genetics, biochemical and molecular biology study of mutant strains of these yeast species. ATH1 gene (coding for acid trehalase) and heat-shock protein genes (HSP16 and HSP104) were shown to play an important role in H. polymorpha thermotolerance. New gene of H. polymorpha (ETT1) was identified conferring tolerance to high temperature and ethanol. H. polymorpha transformant overexpressing ETT1 was shown 3-10-fold more resistant to ethanol, AZC and heat-shock. The positive effect on H. polymorpha ethanol tolerance due to heterologous gene expression of MPR1 gene of S. cerevisiae was shown. It was shown that the overexpression of PDC1 gene coding for pyruvate decarboxylase can be used as one of the improvements of high-temperature fermentation of xylose in H. polymorpha. Methods of molecular genetics were developed for ethanol tolerant yeast D. bruxellensis (transformation and reporter system). Methods: microbiological, biochemical, molecular genetic, mathematical statistics. Area of use: applied microbiology, biotechnology, biochemistry.