Methods for the positive selection of ethanol overproducing mutants from Saccharomyces cerevisiae

摘要

Described herein are new approaches for the selection of S. cerevisiae strains with increased ethanol production from hydrolyzed starch derived sugars. An industrial production strain of Saccharomyces cerevisiae AS400 was subjected to positive selection of mutants resistant to toxic concentrations of oxythiamine, trehalose, 3-bromopyruvate, glyoxylic acid, and glucosamine. The selected mutants are characterized by 5-8% increase in ethanol yield (g g⁻¹ of consumed glucose) as compared to the parental industrial ethanol-producing strain. A multiple-step selection approach that consisted of the sequential selection using glyoxylic acid, glucosamine and bromopyruvate as selective agents resulted in a 12% increase in ethanol yield during fermentation on industrial media. These results indicate that the selection methods provided herein are useful for producing a variety of strains that are promising candidates for industrial ethanol production.