Effect of ultraviolet radiation on physiological and biochemical properties of yeast Saccharomyces cerevisiae during fermentation of ultradispersed starch raw material

Background: Study of correlation between pretreatment of yeast with ultraviolet radiation and efficiency of further fermentation of wort made of ultrafine grain particles to ethanol. Results: We investigated three races of industrial yeast Saccharomyces cerevisiae (native and irradiated by ultraviolet). Physiological properties during fermentation of starchy wort were tested in all variants. It was shown that activation of the yeast by ultraviolet radiation allows to further increase the ethanol yield by 25% on average compared with the native yeast races when using thin (up to micro- and nano-sized particles) or standard grain grinding. Conclusions: Using mechanical two-stage grinding of starchy raw materials and ultraviolet pretreatment of yeast, the efficiency of saccharification of starch and fermentation of wort to ethanol was increased.

Integration and Expression of BGL1 Gene from Saccharomy-copsis fibuligera in Industrial Saccharomyces cerevisiae / 微生物学通报

The recombinant plasmid pPIC-gpd-bgl-hyg was constructed, which contained GPD2 promotor and terminator from industrial yeasts Saccharomyces cerevisiae, ?-glucosidase gene (BGL1) from Sac-charomycopsis fibuligera and hyg from hygromycin as the selected marker. With the yeast’s high efficiency of homologous integrated, the BGL1 gene was successfully integrated into industrial yeasts S. cerevisiae. The recombined yeast could grow on the cultures with the cellobiose as a sole carbon source, and the ?-glucosidase activity achieved 0.764 U/mL after 48 hours’ cultivation. In the experiments of VHG ethanol fermentation, the cellobiose concentration in broth of recombined yeast was 80% lower than that of indus-trial yeast.