Consecutively combined mutagenesis of Saccharomyces cerevisiae and a rapid screening method of high-yielding ethanol mutants

To obtain a high productive industrial strain of Saccharomyces cerevisiae,consecutively combined mutagensis by DES and UV was conducted on the strain QD,and the target mutants were screened by the improved fermentation tube-gas-gathering method and quantitative determination of ethanol. Simultaneously,the mutagenesis method was compared with the routine mutation way. The results showed that the maximum value of positive mutation rate of consecutively combined mutagenesis was 18.9%,which is approximately 21.2% higher than the corresponding mutation rate obtained by the routine mutation way whose value was about 15.6%,which means that relatively higher positive mutation rate could be achieved from this new mutagenesis method. And the improved screening method could be used to rapidly select the target mutants. Furthermore,one high-yield-ethanol mutant was acquired by the new mutagenesis method in the test,and its ethanol yield reached 9 720 mg/100 mL in the fermentative medium of sugarcane juice,which was 6.0%higher than the corresponding yield of the mutant gained by the routine mutation way(the value was about 9 170 mg/100 mL).Conclusively,compared with routine mutation way,high positive mutation rate and high yield mutant can be obtained by the consecutively combined mutagenesis simultaneously.