Mutagenesis Breeding Of A High-ethanol-yield Saccharomyces Cerevisiae Strain By Combining UV And Microwave Irradiation

In this paper, in order to improve ethanol production of the strains of Saccharomyces cerevisiae, Saccharomyces cerevisiae S31206 was irradiated by combined UV and microwave, and a mutant strain called Y-9-3, which produced alcohol up to 18.0% and increased 68.2%,higher than the starting strain was selected by ultraviolet light (30W) irradiation 160s, microwave irradiation (700W) 50s. In addition, the stability of alcohol production of Y-9-3 has been studied and the tests showed that the mutant strain has a higher alcohol-production ability, which could achieve 17.3% on average. It has a good stability of fermentation and also has a good application in industries.In addition, the optimum fermentation conditions of the mutant strain were studied. The fermentation time, fermentation temperature, the concentration of glucose in fermentation medium, and the amount volume of bacteria were studied, and determined the best fermentation conditions of mutant strain: fermentation time 3d, fermentation temperature 32℃, the glucose concentration of fermentation medium 25g/100mL, and bacteria inoculation volume 1.5mL/100mL.Finally, the irradiation treatment on Saccharomyces cerevisiae cells has been studied in this paper. The results of the irradiation treatment on Saccharomyces cerevisiae cells showed that irradiation induced treatment on the impact the morphology of Saccharomyces cerevisiae cells pronounced, leading to the surface of cells not smooth, uneven, and some cells also were apparent damaged, resulting in leakage of intracellular proteins and nucleic acids, so guess irradiation treatment resulted in Saccharomyces cerevisiae cell membranes damaged, resulting in the osmotic pressure of the cell changed.In this paper, a high-ethanol-yield Saccharomyces cerevisiae strain Y-9-3 was acquired by UV irradiation and microwave mutation from Saccharomyces cerevisiae 31206. Determined the above optimal conditions of fermentation process after the stability of mutant was tested, and it provided some theoretical basis for industry.