Mutation breeding for productive yeast strains through a novel method: High-energy-pulse-electron-beam

High-energy-pulse-electron beam (HEPE) has primarily been used in pulse radiolysis and material surface modification to date. In this study, we applied HEPE in yeast ( Saccharomyces cerevisiae ) breeding and investigated its biological effects on plasmid DNA and yeast plasma membrane. A thermo-tolerant and high- ethanol-yield yeast strain YE2 was obtained after HEPE radiation and temperature selection, with optimum temperature improved 2°C and ethanol yield improved 25.5%, suggesting that it is a promising candidate for cellulose-derived ethanol production. DNA-lesion analysis showed that the G-value of HEPE radiation for double-strand breaks (DSB) formation is 2.5 × 10 −10 Gy −1 Da −1 , which is 5 times that of γ-radiation, while there was only 12.1% plasma membrane damage found even at high dosage of 750 Gy.