过表达NADH激酶基因对酿酒酵母乙醇发酵的影响

Effects of overexpression of NADH kinase gene on ethanol fermentation by Saccharomyces cerevisiae

摘要:

甘油是酿酒酵母乙醇代谢途径中的主要副产物，降低甘油生成，可以提高乙醇的产率和原料的利用率。以工业酒精酵母单倍体S1 (MATa) 为研究对象，构建了一个4.5 kb左右的基因敲除突变盒gpd2Δ::PGK1PT-POS5-HyBR，利用醋酸锂转化法转入S1，得到重组菌S3 (gpd2Δ::PGK1PT-POS5-HyBR)，使得工业酒精酵母在敲除GPD2的同时整合过表达了NADH激酶基因POS5。结果表明，在150 g/L的葡萄糖摇瓶发酵实验中，重组菌S3在不影响菌株生理特性的条件下，乙醇得率 (g ethanol/g glucose) 比原始菌株S1提高了8%，甘油得率 (g glycerol/g glucose) 降低了33.64%。本研究证明过表达NADH激酶基因可降低乙醇发酵中副产物甘油的生成并提高乙醇得率。

Abstract:

Glycerol is the main byproduct in ethanol production by Saccharomyces cerevisiae. In order to improve ethanol yield and the substrate conversion, a cassette about 4.5 kb for gene homologous recombination, gpd2Δ::PGK1PT-POS5-HyBR, was constructed and transformed into the haploid strain S. cerevisiae S1 (MATa) to replace the GPD2 gene by POS5 gene. The NADH kinase gene POS5 was successfully expressed in the recombinant strain S. cerevisiae S3. Comparing with the parent strain, the recombinant strain S. cerevisiae S3 exhibited an 8% increase in ethanol production and a 33.64% decrease in glycerol production in the conical flask fermentation with an initiatory glucose concentration of 150 g/L. Overexpression of NADH kinase gene seems effective in reducing glycerol production and increasing ethanol yield.