FAS2基因过表达对酿酒酵母风味酯生成能力的影响

研究了共表达脂肪酸合成酶复合体中α亚基的编码基因FAS2和β亚基的编码基因FAS1对酿酒酵母产风味酯的影响。前期实验室构建的过表达FAS1基因的菌株α5F-FAS1和α5O-FAS1可以提高酿酒酵母产中链脂肪酸乙酯的含量，本研究以这两株菌为出发菌株过表达FAS2基因，相比较α5F-FAS1菌株，己酸乙酯、辛酸乙酯、癸酸乙酯分别提升了154.31%，65.22%和23.53%；相比较α5O-FAS1菌株，己酸乙酯、辛酸乙酯、癸酸乙酯、十二酸乙酯分别提升了17.34%，30.71%，27.12%和28.13%。结果显示共表达FAS1和FAS2基因可以更进一步的提升酿酒酵母中链脂肪酸乙酯的产量。同时，本研究还发现，过表达FAS1可以提高乙酸乙酯的生成量。为了探究本现象产生的初步机理，通过RT-PCR测定了合成与利用乙酰辅酶A相关基因的表达量，实验结果表明，过表达FAS1导致的乙酸乙酯生成量上升的现象主要是由于过表达FAS1使得ATF1的表达量上升造成的。
The effects of fatty acid synthase 1 gene (FAS1) and fatty acid synthase 2 gene FAS2 overexpression on medium cahin fatty acid ethyl esters (MCFAEEs) in Saccharomyces cerevisiae were investigated. Previous experiment showed that FAS1 gene-expression strains, α5F-FAS1 and α5O-FAS1, could improve the production of MCFAEEs in S. cerevisiae. The 154.31% and 65.22% improvement of ethyl caproate and ethyl octanoate production and 23.53% increasement of ethyl caprate accumulation were observed in the Co-overexpression of FAS1 and FAS2 with FAA1 deletion engineered strain FF1F2 compared to strains α5F-FAS1. Consistent with this effect, the Co-overexpression strain OF1F2 achieved 17.34%, 30.71% and 27.12% increasement of the three substances mentioned above and 28.13% improvement of ethyl dodecanoate, respectively, compared to strains α5O-FAS1. The results showed that FAS1 and FAS2 gene co-overexpression could further enhance the yield of MCFAEEs in S. cerevisiae. At the same time, we also found that overexpression of FAS1 gene can improve the production of ethyl acetate. To explore the preliminary machnism of this phenomenon, the relative expression level of Acetyl-CoA related genes was measured by RT-PCR. The results showed that the increase in the amount of ethyl acetate produced by FAS1 overexpression is mainly attributed to the up-regulation of ATF1 gene expression.