Production of free monounsaturated fatty acids by metabolically engineered Escherichia coli

Biotechnology for Biofuels

Mo Xian¹  Jiming Wang¹  Haibo Zhang¹  Xin Xu¹  Wei Liu¹  Yujin Cao¹ 

[1]CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China

关键词: acetyl-CoA carboxylase;    acyl-CoA synthetase;    Fatty acid desaturase;    Thioesterase;    Free monounsaturated fatty acids;   

Others  :  792683
DOI  :  10.1186/1754-6834-7-59

 received in 2013-08-18, accepted in 2014-03-17,  发布年份 2014

【 摘 要 】

Background

Monounsaturated fatty acids (MUFAs) are the best components for biodiesel when considering the low temperature fluidity and oxidative stability. However, biodiesel derived from vegetable oils or microbial lipids always consists of significant amounts of polyunsaturated and saturated fatty acids (SFAs) alkyl esters, which hampers its practical applications. Therefore, the fatty acid composition should be modified to increase MUFA contents as well as enhancing oil and lipid production.

Results

The model microorganism Escherichia coli was engineered to produce free MUFAs. The fatty acyl-ACP thioesterase (AtFatA) and fatty acid desaturase (SSI2) from Arabidopsis thaliana were heterologously expressed in E. coli BL21 star(DE3) to specifically release free unsaturated fatty acids (UFAs) and convert SFAs to UFAs. In addition, the endogenous fadD gene (encoding acyl-CoA synthetase) was disrupted to block fatty acid catabolism while the native acetyl-CoA carboxylase (ACCase) was overexpressed to increase the malonyl coenzyme A (malonyl-CoA) pool and boost fatty acid biosynthesis. The finally engineered strain BL21ΔfadD/pE-AtFatAssi2&pA-acc produced 82.6 mg/L free fatty acids (FFAs) under shake-flask conditions and FFAs yield on glucose reached about 3.3% of the theoretical yield. Two types of MUFAs, palmitoleate (16:1Δ9) and cis-vaccenate (18:1Δ11) made up more than 75% of the FFA profiles. Fed-batch fermentation of this strain further enhanced FFAs production to a titer of 1.27 g/L without affecting fatty acid compositions.

Conclusions

This study demonstrated the possibility to regulate fatty acid composition by using metabolic engineering approaches. FFAs produced by the recombinant E. coli strain consisted of high-level MUFAs and biodiesel manufactured from these fatty acids would be more suitable for current diesel engines.

【 授权许可】

   
2014 Cao et al.; licensee BioMed Central Ltd.

【 图 表 】

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