Isolation of an osmotolerant ale strain of Saccharomyces cerevisiae

Saccharomyces cerevisiae (ale strain) grown in batch culture to stationary phase was tested for its tolerance to heat (50 degrees C for 5 min), hydrogen peroxide (0.3 M) and salt (growth in 1.5 M sodium chloride/YPD medium). Yeast cells which have been exposed previously to heat shock are more tolerant to hydrogen peroxide and high salt concentrations (1.5 M NaCl) than the controls. Their fermentative activity as judged by glucose consumption and their viability, as judged by cell number and density have higher levels when compared with cells not previously exposed to heat shock. Experimental conditions facilitated the isolation of S. cerevisiae ale strain, which was tolerant to heat, and other agents such as hydrogen peroxide and sodium chloride.