Characterization of an interesting novel mutant strain of commercial Saccharomyces cerevisiae

Abstract

The yeast strains that are resistant to high concentration of ethanol have biotechnological benefits and are<br />suitable models for physiology and molecular genetics research fields. A novel ethanol-tolerant mutant strain,<br />mut1, derived from the commercial Saccharomyces cerevisiae showed higher ethanol production, and also<br />demonstrated resistance to ethanol but not to other alcohols, such as methanol, 2-propanol, and 1-<br />butanol. To characterize mut1, the strain's resistance to other organic compounds and osmotic and cell wall<br />stresses were examined. The growth of the mut1 strain in the presence of ethyl n-caproate and 3-methyl butyl<br />acetate, which were metabolic derivatives of ethanol, was found to be less than the wild type. On the other<br />hand, the growth of the mut1 strain in the presence of 50% (w/v) sucrose and 1M NaCl was similar to that of<br />the wild type. The sensitivity to cell wall digestive enzyme, zymolyase, was also similar in both wild and<br />mut1 strains. Finally, the mut1 strain showed resistance to homocysteine and serine but was sensitive to<br />methionine. These results suggest that the ethanol resistance of the mut1 strain may be more related to<br />the ethanol metabolic and signalling pathways rather than the enhanced stress resistances relating to the<br />membrane or cell wall compositions.<br /><br />