Industrial Saccharomyces Cerevisiae Met10 Gene Knock In Addition To And Used For Industrial Production Of A Feasibility Study

Beer is abundant in vitamins and mineral substance, beneficial to health in appropriate demand, so it is called as nutritious food. Ingredients of beer are very nutritious and have good effects on precaution and cure for some diseases.Beer aging is still a serious problem to the beer brewing because it could shorten the shelf life and change the good flavor of beer. So many researchers were very interested in this problem, and lots of measures had been taken to prevent beer aging. Using a good strain of Saccharomyces cerevisiae in beer brewing may be one of the best ways to solve this problem.Sulfite is widely used as an antioxidant in food and beer industry. In beer brewing. sulfite has the additional role of stabilizing the flavor by forming adducts with aldehydes. During the beer brewing, the concentration of sulfite in beer is rather low because sulfite can be deoxidized by sulfite reducase. In S.cerevisae, met10 gene encodes a subunit of sulfite reducase. Partial or full deletion of met 10 gene resulted in inactivity of sulfite reducase. so sulfite couldn't be deoxidized and would be accumulated in beer. Beer brewed using metlO gene mutant S.cerevisae strain may prevent beer oxidation and stabilize the beer flavor.A foreign gene targeting cassette was constructed from plasmid pYES2 and S.cerevisae by LFH-PCR. It consisted of a G418-resistance gene with long flanking homology regions of met 10 gene.It was transferred into the industrial strain through the procedure of intact cell transformation. It integrated into S.cerevisae genome due to homologous recombination. Thus met 10 gene was disrupted and an industrial strain with met 10 gene knockouted was obtained.The original strain and the met 10 gene-knockouted strain differed in growth rate and fermentation property in l.000L fermentation tanks. The latter grew and fermented faster than the former, at the same time the concentration of acetaldehyde in the beer production of the latter was lower than that of the former, though dissociative sulfite concentration in both beer production was almost at the same level.On the contrary, the former's ability to reduce diacetyl was better than the latter's. The beer production with the gene-knockouted strain tasted better than that of the original strain in the 100,000L fermentation tank, and could be stored for a long time.