IMPROVEMENT OF ETHANOL YIELD AND REDUCTION OF BIOMASS ACCUMULATION IN THE RECOMBINANT STRAIN OF SACCHAROMYCES CEREVISIAE OVEREXPRESSING ATP DEGRADING THE ENZYMES

摘要

A new approach for increase of ethanol yield during alcoholic fermentation via decrease of biomass accumulation by using ATP degrading enzymes is described. The part of the Saccharomyces cerevisiae SSB1 gene coding for cytosolic ATPase domain of ribosome associated chaperon cloned into expression cassette under control of the glycerol-3-phosphate dehydrogenase gene (GPD1) promoter was introduced into the S. cerevisiae BY4742 strain. The recombinant strains were tested for their ability to grow and produce ethanol during glucose anaerobic and aerobic cultivations. Strains overexpressing ATPase domain of SSB1 possessed decreased concentration of intracellular ATP. They accumulated elevated amounts of ethanol and were characterized by decreased biomass accumulation as compared to the wild-type strain under both anaerobic and aerobic conditions. Similarly, the apyrase gene apy from E. coli encoding ATP/ADP hydrolyzing phosphatase and ATPase domain of SSB1 gene of S. cerevisiae were co-expressed under the control of galactose-inducible GAL1 promoter. The recombinant S. cerevisiae strains revealed slight reduction of biomass accumulation, while specific ATPase activity, ethanol accumulation and yield during alcoholic galactose fermentation under semi anaerobic conditions were increased.