EVALUATION OF ETHANOL AND BIOMASS PRODUCTION RATE BY DIFFERENT $SACCHAROMYCES~CEREVISIAE$ STRAINS DEPENDING ON EXTERNAL pH AND TEMPERATURE

Bioethanol production is in high demand due to its potential replace transportation fuel and ability be renewable long-lasting. Therefore, the bioconversion of fermentable sugars ethanol central importance. The work aimed explore yeast properties changes during fermentation at different pHs temperature conditions. Biomass production, specific growth rate (SGR), products, metabolite composition quantity were studied 25℃, 30℃, 37℃ as well pH 5 6.5 SGR data shows that 25℃ 30℃ optimal for biomass production. At 5.0–6.5, ATCC 9804 strain almost 2 times exceeds same parameter another strain. highest was detected 5. Ethanol by increases decreases contrast 6.5, where within 30–37℃ range have no significant effect on it both strains. concent­ra­tion extracellular medium reached ~117 mM case 13007 strain, whereas 1.4-fold lower. Both strains had substrate assimilation rate. Glycerol reduces with increasing pH; glycerol concentration (6.1 mM) observed 32 h reaches 5.5 24 under free energy 2.3-fold 4-fold higher compared acetate processes Gibbs lowest value 5, suggesting a preference alcoholic metabolic pathway these after hours 37°C ΔG = 173.9 kJ/mol. Obtained highlights stress mechanisms regulation can used improving genetic modification tools.