Interaction Of UV Radiation With Temperature And Influence Of It On The Ethanol Production-enhancing Mutation In Yeast

Saccharomyces cerevisiae Hs27a strains were first treated by exposure to UV radiation, and then incubated in a series of temperatures between 25℃and 40℃for 2-3d. 100 strains were picked out randomly from colonies on plates under each culture temperature. Subsequently, fermentation were carried out according to the way applied in the industry using the mutants selected after the combined action of UV and temperature to determine the associated effect of the two factors especially for the elevated temperature 40℃on the enhancement to the ethanol production. The average ethanol rise rate was 8.75% for the forward-mutation strains at 40℃that was defined as mutants that processed a highest alcohol production comparing with original strains in contrast with the hightest one of 6.63% at 31℃. Besides, strains of ethanol rise rate above 10% at the temperature of 40℃account for more than 1/3(34.3%), while strains from 40°C have the highest reducing rate of 34.3% among all the strains with ethanol production reduced by 10%. As what happened in strains from 40℃, the average ethanol reducing rate of 40℃were still the highest one about 32.9%. Furthermore the effect of temperature on the forward-mutation rate that refered to the rate of forward-mutation strains in all the strains was not so obvious.The progeny strains and the original strain were tested by RAPD of total DNA with 15 primers. It was showed that the variations occurred in the chromosomal DNA of the yeast strains grown at 40℃were more than that at 31℃. The similarity of 40℃strains through RAPD analysis was 52.9%,compared with 73.1% at 31%. The results above demonstrated that stress temperature(40℃in this paper) impose significant influence on the variations of DNA after UV radiation.In addition, strains of 40℃and 31℃was subject to high temperature fermentation at 40℃. Approximate 10% in the average ethonal enhancement was observed which was of great significance.The method, interaction of high temperature with UV radiation, enhanced the efficiency of UV irradiation breeding of high-producing ethanol Hs27a strain and put forward a new way researching into the mechanisms of mutation formation in Saccharomyces cerevisiae cells irradiated with UV.