Engineering Escherichia coli FAB system using synthetic plant genes for the production of long chain fatty acids

Elias Kassab,Thomas B Brueck,Martina Haack,Monika Fuchs,Norbert Mehlmer

doi:10.1186/s12934-019-1217-7

Elias Kassab, Thomas B Brueck + Show 3 more

Open Access

https://doi.org/10.1186/s12934-019-1217-7

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Abstract

BackgroundSustainable production of microbial fatty acids derivatives has the potential to replace petroleum based equivalents in the chemical, cosmetic and pharmaceutical industry. Most fatty acid sources for production oleochemicals are currently plant derived. However, utilization of these crops are associated with land use change and food competition. Microbial oils could be an alternative source of fatty acids, which circumvents the issue with agricultural competition.ResultsIn this study, we generated a chimeric microbial production system that features aspects of both prokaryotic and eukaryotic fatty acid biosynthetic pathways targeted towards the generation of long chain fatty acids. We redirected the type-II fatty acid biosynthetic pathway of Escherichia coli BL21 (DE3) strain by incorporating two homologues of the beta-ketoacyl-[acyl carrier protein] synthase I and II from the chloroplastic fatty acid biosynthetic pathway of Arabidopsis thaliana. The microbial clones harboring the heterologous pathway yielded 292 mg/g and 220 mg/g DCW for KAS I and KAS II harboring plasmids respectively. Surprisingly, beta-ketoacyl synthases KASI/II isolated from A. thaliana showed compatibility with the FAB pathway in E. coli.ConclusionThe efficiency of the heterologous plant enzymes supersedes the overexpression of the native enzyme in the E. coli production system, which leads to cell death in fabF overexpression and fabB deletion mutants. The utilization of our plasmid based system would allow generation of plant like fatty acids in E. coli and their subsequent chemical or enzymatic conversion to high end oleochemical products.

Highlights

Sustainable production of microbial fatty acids derivatives has the potential to replace petroleum based equivalents in the chemical, cosmetic and pharmaceutical industry
In the ketoacyl acp synthase II (KASII) clones, we detected an increase in unsaturated fatty acids, long chain fatty acids (i.e. C16:1 and C18:1) with regard to the wildtype BL21 (DE3) strain
We demonstrate that the overexpression of the A. thaliana β-ketoacyl-[acyl carrier protein] synthase I (KASI) gene, the homologue of 3-oxoacyl-[acyl-carrier-protein] synthase 1 (FabB), in wild type E. coli shows an improvement in the overall production of saturated fatty acids with increases in myristic, palmitic acid, and stearic acid in addition to cis-vaccenic acid

Summary

Introduction

Sustainable production of microbial fatty acids derivatives has the potential to replace petroleum based equivalents in the chemical, cosmetic and pharmaceutical industry. Most fatty acid sources for production oleochemicals are currently plant derived. Utilization of these crops are associated with land use change and food competition. To circumvent the ecological impact of plant oil production for generation of oleochemical building blocks, there is an increasing industrial demand for microbial generated fatty acids derived from bacteria, yeast or algae [1, 2] The chain length and degree of saturation of renewable fatty acids channels their use into either the biofuel, pharmaceutical or chemical industry. The sustainable production of microbial fatty acids and their derivatives as a renewable alternative to petroleum and other natural hydrocarbons has been the research focus over the past decades [1, 3, 5,6,7,8,9,10]. A profound understanding of the E. coli fatty acid biosynthesis pathway and the enzymes

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