优化硫酯酶表达提高大肠杆菌脂肪酸乙酯的生物合成效率

Improvement of fatty acid ethyl ester production by optimizing thioesterase expression

摘要:

利用基因工程大肠杆菌直接从头生物合成脂肪酸乙酯 (生物柴油) 的相关研究引起了国内外研究人员的广泛关注。在本课题组已经构建的能够从头合成脂肪酸乙酯的大肠杆菌菌株KC3的基础上，通过替换表达不同来源的硫酯酶，发现表达来源于香樟树的硫酯酶Cc FatB1基因能够提高脂肪酸乙酯产量。进一步通过共表达Cc FatB1和大肠杆菌硫酯酶tesA’基因，以及启动子优化，获得了高产脂肪酸乙酯工程菌株KC4。KC4菌株在摇瓶条件和发酵条件下的单位生物量脂肪酸乙酯产率分别为21.4 mg/ (L?OD600)和31.16 mg/ (L?OD600)。该工程菌株的构建进一步提高了脂肪酸乙酯产量，显示了通过基因工程改造大肠杆菌从头合成生物柴油的应用潜力。

关键词:硫酯酶，脂肪酸乙酯，大肠杆菌，基因工程

Abstract:

Biosynthesis of fatty acid ethyl ester (FAEE) by genetically engineered Escherichia coli has attracted extensive attentions from scientific community. In this study, we evaluated the effects of thioesterase with different origins on FAEE production and the results show that Cc FatB1 from Cinnamomum camphorum is better than tesA’ from E. coli for FAEE production. Then, the optimized FAEE-producing strain KC4, with 21.4 mg/(L?OD600) FAEE production under flask condition and 31.16 mg/(L?OD600) under 5 L fermentation condition, was constructed by co-expression of Cc FatB1 and tesA’. Compared with the reported FAEE-producing strain KC3, KC4 possesses the higher FAEE productivity.

Key words:thioesterase, fatty acid ethyl esters (FAEE), Escherichia coli, genetic engineering