Overproduction And Expression Of Alcohol Dehydrogenase Ⅰ In S.cerevisiae

The beer flavor was made up of diversified ingredient, mainly had carbonyl compound, hops acid, fatty acid, organic acid, ester, amino acid, polyphenol and so on. Some literatures reported in the beer probably had 50 kinds aldehyde and 54 kinds ketones, then only the minority carbonyl compounds content coμld approach its flavor threshold value, the most aldehyde flavor threshold value was lower than corresponding mellow 2-3 time. In the beer the carbonyl compound content highly, coμld have the adverse effect to the beer flavor. But the acetaldehyde was in the beer carbonyl compound the content highest compound.Μsually the acetaldehyde was considered to make to lose the beer flavor, when the acetaldehyde's content surpassed 15mg/l, could bring the rotten green grass taste, affected the feeling in the mouth.This article would expand increases the alcohol degydrase I (ADH I), then the fixed-point conformity to beer yeast's V chromosome URA3 place, discussed this fixed-point conformity, the excess expression condition and the result, and screened reduces the acetaldehyde characteristic, the performance stable yeast project fungus. At the same time increased the some content for the beer yeast ADH I gene's molecular biology research.。The ethanol dehydrogenase enzyme activity of improved the Saccharomyces cerevisiae improved by about four times compared with original saccharomyces cerevisiae. The quantity of acetic aldehyde has decreased by 75%,acetyl has decreased by 25%, the attenuation has rised by 16%. After measurating the flavor material of improved strain through the gas chromatograph. The total alcohol content increases by 60%. Total ester content does not change much. It saids improved strain flavor material has not changed .