Genetically Engineered Strains Of Low-alcohol Beer Construction And Analysis Of Fermentation Parameters

Low alcohol beer has similar taste to normal beer, which can drink a lot without Inebriating. At the same time, low alcohol beer matches the fashion that consumers pay much attention to their healthy, and women allergy to alcohol and men like low alcohol beer so much, so low alcohol beer has a good future.The key index sign to low alcohol beer is alcohol content which relates to the quality of beer. How to solve the content of alcohol in beer is the key to product low alcohol beer. Now, there are several kinds of method to reduce the content of alcohol in beer, one of the most ideal methods is to construct low alcohol beer genetic engineering yeast, through reforming the yeast itself to produce low alcohol beer.Alcohol dehydrogenaseⅠ(ADHⅠ) is the key enzyme that control alcohol content in yeast metabolism, catalysts Acetaldehyde changes to alcohol. The vitality of dehydrogenaseⅠrelate to the alcohol content in yeast. Reducing alcohol content by making use of gene knockout technique to break dehydrogenaseⅠ, then transforming a lower vitality dehydrogenaseⅠinto yeast to construct low alcohol beer genetic engineering yeast.A foreign gene targeting cassette was constructed from plasmid pCAMBIA by LFH-PCR. It consisted of Hyb-resistance gene with long flanking homology regions of ADHⅠgene. It was transferred into yeast (HDY-01) by LiAc transformation method. It integrated into yeast (HDY-01) genome due to homologous recombination. Thus ADHⅠgene was disrupted and yeast (ΔADHⅠ) with ADHⅠgene knockouted was obtained. Then plasmid pYC6/CT-BADHⅠwas constructed which consisted of BADHⅠgene cloned from bacillus subtilis genome and plasmid pYC6/CT. Finally, low alcohol beer genetic engineering yeast (BADHⅠ-ΔADHⅠ) was constructed through transformed plasmid pYC6/CT-BADHⅠinto yeast (ΔADHⅠ)by LiAc transformation method.Three types of yeast are differed in growth and fermentation productions content in fifteen days'fermentation experiment. Yeast (BADHⅠ-ΔADHⅠ) can keep more numbers in the fermentation courses than the other two types yeast, at the same time the concentration of acetaldehyde, alcohol and diacetyl and pentanedione are lower than yeast (HDY-01), meet the standard of high-quality low alcohol beer.The successful realization of this research, constructs the genetic engineering yeast that fit for beer production, extends the source of Saccharomyces cerevisiae. As the source of the yeast come from commercial run, after reforming successfully, the production facility need not to be changed and the capacity factor and the economic effect can be improved greatly.