RESUMO
By UV induced mutagenesis of protoplasts of Saccharomyces cerevisiae strain f4, f5 and f6, and screening on plates containing different concertration of ethanol at different temperature, we obtained improved strains, such as f4.2, f5.1, f6.2, f4.5. By using a DES to deal with all the improved strains, We obtained two mutants, f5.1.1 and f4.2.1,which have improved ethanol torlerance. We made use of genome shuffling to generate improved strains in this work. We shuffled twice these improved strains by protoplast fusion and finally obtained strains with higher temperature and ethanol tolerance. we also identified shuffled strains that produced more ethanol by shake-flask experments. At the 35℃, the ethanol yield of R24 strain got to 12.93% (W/V), and were almost 5% higher than that of stain f4.