Development, Manufacturing and Fermentation Performance of Novel Hybrid Yeast Strains in Industrial Ethanol Fermentations

Ethanol fermentation processes are functionally dependent on biocatalytic activity of living microorganism, Saccharomyces cerevisiae (yeast). Development of novel stable yeast strains with stable genotypes, resistant to stress and sometimes possessing additional metabolic activities beside central metabolism pathways involved in ethanol metabolism bring additional benefits when employed in the industrial setting. Critically, genetically stable yeast strains with improved tolerances to the industrially relevant stress factors allow for yeast recycling without compromising their metabolic capabilities. While in some processes use of genetically modified organism is permitted significant need remains for implementing non genetically modified microorganism. Implementation of common classical hybridization methods with robust screening allows for selection of hybrids with targeted phenotypes. When combined with genotyping strain differences can be further characterized. To obtain new families of strains the classical hybridizations methods such as: direct mating, rare mating, and mass mating were used. Combining these hybridization methods with targeted stress focused hybrid screening allowed for selection of hybrids with improve ethanol performance characteristics vs. parental strains. In our case we have obtained genetically stable yeast strains allowing for yeast recycling, improved stress tolerance strains as well as strains with extracellular enzymatic activity. The terminal strain GSYE-GA with its STA1 activity which allows for decrease of commercial glucoamylase (GA) enzyme products use provided for allowing GA reduction in the range of 20-30 % vs. control. This research was supported by public project funding Project Number: POIR.01.01.01-00-1196/17, Marshal Office of the Wielkopolska Region, Poland