High production of fatty alcohols in Escherichia coli with fatty acid starvation

Yilan Liu,Jinjin Chen,Yanyan Wang,Jiemin Zhou,Jianmin Xing,Sha Chen,Maohua Yang,Qinhong Wang,Yanhe Ma,Xianni Qi

doi:10.1186/s12934-016-0524-5

Abstract

BackgroundMicrobial biofuel synthesis attracting increasing attention. Great advances have been made in producing fatty alcohols from fatty acyl-CoAs and fatty acids in Escherichia coli. However, the low titers and limited knowledge regarding the basic characteristics of fatty alcohols, such as location and toxicity, have hampered large-scale industrialization. Further research is still needed.ResultsIn this study, we designed a novel and efficient strategy to enhance fatty alcohol production by inducing fatty acid starvation. We report the first use of deletions of acyl-ACP thioesterases to enhance fatty alcohol production. Transcriptional analysis was conducted to investigate the mechanism of the designed strategy. Then, fatty alcohol production was further enhanced by deletion of genes from competing pathways. Fatty alcohols were shown to be extracellular products with low toxicity. The final strain, E. coli MGL2, produced fatty alcohols at the remarkable level of 6.33 g/L under fed-batch fermentation, representing the highest reported titer of fatty alcohols produced by microorganisms.ConclusionsDeletions of genes responsible for synthesis of fatty acids and competing products are promising strategies for fatty alcohol production. Our investigation of the location and toxicity of fatty alcohols suggest bright future for fatty alcohol production in E. coli.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-016-0524-5) contains supplementary material, which is available to authorized users.

Highlights

Because fatty acids are synthesized in the cytoplasm in E. coli, tesC may play a key role in producing fatty acids
In summary, a fatty alcohol titer of 6.33 g/L was achieved in fed-batch fermentation in E. coli via the deletion of fatty acyl-CoA thioestarase, to starve cells of fatty acids, as well as deletion of lactic dehydrogenase (ldhA), pta and acetate kinase (ackA) from competing pathways
Fatty alcohols were shown to be extracellular products with low toxicity to E. coli. These results indicate a bright future for microbial production of fatty alcohols

Summary

Introduction

Great advances have been made in producing fatty alcohols from fatty acyl-CoAs and fatty acids in Escherichia coli. Microbial production of high-energy fuels has emerged as a viable alternative to conventional fuels [3, 4]. Fatty acids and their derivatives are of particular interest owing to their high caloric value [5]. Fatty alcohols can be produced from fatty acyl-ACPs, fatty acyl-CoAs, or fatty acids through the catalysis of fatty acyl reductase (FAR) [12, 15,16,17]. Great advances have been made in engineering microorganisms to produce fatty alcohols from fatty acyl-CoAs [5, 16] and fatty acids [17].

Methods

Results

Conclusion