Improvement of Acetic Acid Tolerance in Saccharomyces cerevisiae by Novel Genome Shuffling

Abstract

The aim of this study was to obtain new distilling strains of Saccharomyces cerevisiae with increased resistance to acetic acid, and, at the same time, characterized by high ethanol production. The first stage of the research focused on the construction of a parental strains library (4 strains) by carrying out a chemical mutagenesis using ethyl methanesulfonate. As a result, several dozen mutants were obtained, which subsequently were subjected to screening for the fermentation activity and resistance to acetic acid at the concentration of 0.05–0.2% vol/vol. After a total of two rounds of genome shuffling of mutants obtained from a pool of the parental library, 50 fusants were obtained. On the basis of rapid fermentation tests, the quality of the newly obtained strains was assessed. The volumetric ethanol productivity was used as a standard for the fermentation activity of the obtained fusants. In order to confirm the genetic changes expected a genetic analysis by PCR using ISSR primers was performed. This analysis shows that changes within the genome are visible in the case of newly developed strain. This improved strain was characterized by a 60% higher ethanol productivity (120 g/L) compared to the parental strain.