RESPONSE TO THERMAL AND ETHANOL STRESS IN INDUSTRIAL STRAINS OF SACCHAROMYCES CEREVISIAE: EFFECTS ON CELL GROWTH AND PROTEIN PRODUCTION

Abstract

The synergism between thermal and ethanol stress directly affects the functionality and survival of yeasts in industrial environments, compromising their cellular physiology. Therefore, this study aims to compare the proteins associated with thermal and ethanol stress, as well as to investigate the impacts of these factors on cell growth and total protein production. The Fleischmann®, Santa Adélia, and Pedra-2 yeasts were cultivated in 2% YPD medium. The biomass was recovered by centrifugation and inoculated in sugarcane juice at 22ºBrix, pH 5.0, and incubated at 30 and 40ºC, with ethanol concentrations ranging from 0, 5, 12, and 16% (v.v-1). Lysis occurred in Tris-HCl and glass beads, and total protein quantification was performed using the Bradford method, followed by readings in a spectrophotometer at 595 nm. Heat shock proteins (HSPs), especially HSP70 and HSP104, play a crucial role in cellular protection and maintenance under adverse conditions. The Fleischmann® lineage showed lower tolerance, with a significant reduction in cell growth. On the other hand, the Pedra-2 lineage demonstrated greater robustness, standing out for its greater biomass production and stress tolerance. Principal component analysis (PCA) confirmed the correlation between total protein production and stress tolerance, consolidating the Pedra-2 lineage as the most promising for industrial applications. This study provides valuable contributions to understanding the interaction of heat shock proteins with severe stress factors in industrial yeasts, with the aim of improving efficiency and promoting sustainability in fermentation processes.