A New Simple Method for Isolating Multistress-Tolerant Semidominant Mutants of Saccharomyces cerevisiae by One-Step Selection under Lethal Hydrogen Peroxide Stress Condition

Tolerance of microorganisms to diverse stresses (i.e., multistress tolerance) is a very useful property with industrial applications. We have developed a simple method for isolating multistress-tolerant semidominant mutants of the budding yeast Saccharomyces cerevisiae by one-step selection under lethal hydrogen peroxide (H2O2) stress condition, which we named the lethal concentration of H2O2 (LCH) method. This method involves simply isolating colonies after plating of mutagenized S. cerevisiae cells, which are cultivated overnight in liquid media, on agar plates containing a lethal concentration of H2O2 for the wild-type strain. Phenotypic and genetic analyses of the ten strains isolated by this method revealed that two strains exhibiting stress tolerance to H2O2, ethanol, heat shock, salt, organic solvent, freeze-thaw, chronological aging, and high concentrations of glucose possess semidominant and distinct single-gene mutations designated as MLT1-1 (multistress tolerance) and MLT2-1, which are responsi...