Stepwise metabolic engineering of Escherichia coli to produce triacylglycerol rich in medium-chain fatty acids

Biotechnology for Biofuels

Xue-Rong Zhou¹  Surinder Singh¹  Lin Xu²  Lian Wang²  Xia Wan²  Feng-Hong Huang²  Wen-Chao Chen²  Zhe Hu³ 

[1] CSIRO Agriculture & Food;Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences;State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University;

关键词: Escherichia coli;    Triacylglycerol;    Medium-chain fatty acid;    Acyltransferase;    Acyl-ACP thioesterase;    Lipid droplet;   

DOI  :  10.1186/s13068-018-1177-x

来源: DOAJ

【 摘 要 】

Abstract Background Triacylglycerols (TAGs) rich in medium-chain fatty acids (MCFAs, C10–14 fatty acids) are valuable feedstocks for biofuels and chemicals. Natural sources of TAGs rich in MCFAs are restricted to a limited number of plant species, which are unsuitable for mass agronomic production. Instead, the modification of seed or non-seed tissue oils to increase MCFA content has been investigated. In addition, microbial oils are considered as promising sustainable feedstocks for providing TAGs, although little has been done to tailor the fatty acids in microbial TAGs. Results Here, we first assessed various wax synthase/acyl-coenzyme A:diacylglycerol acyltransferases, phosphatidic acid phosphatases, acyl-CoA synthetases as well as putative fatty acid metabolism regulators for producing high levels of TAGs in Escherichia coli. Activation of endogenous free fatty acids with tailored chain length via overexpression of the castor thioesterase RcFatB and the subsequent incorporation of such fatty acids into glycerol backbones shifted the TAG profile in the desired way. Metabolic and nutrient optimization of the engineered bacterial cells resulted in greatly elevated TAG levels (399.4 mg/L) with 43.8% MCFAs, representing the highest TAG levels in E. coli under shake flask conditions. Engineered cells were observed to contain membrane-bound yet robust lipid droplets. Conclusions We introduced a complete Kennedy pathway into non-oleaginous E. coli towards developing a bacterial platform for the sustainable production of TAGs rich in MCFAs. Strategies reported here illustrate the possibility of prokaryotic cell factories for the efficient production of TAGs rich in MCFAs.

【 授权许可】

Unknown