Enhanced Production of Fatty Acid Ethyl Ester with Engineered fabHDG Operon in Escherichia coli.

Ziaur Rahman,Sun Chang Kim,Muhammad Faisal Siddiqui,Almando Geraldi,Bong Hyun Sung,Abid Ali,Javed Nawab

doi:10.3390/microorganisms7110552

Abstract

Biodiesel, or fatty acid ethyl ester (FAEE), is an environmentally safe, next-generation biofuel. Conventionally, FAEE is produced by the conversion of oil/fats, obtained from plants, animals, and microorganisms, by transesterification. Recently, metabolic engineering of bacteria for ready-to-use biodiesel was developed. In Escherichia coli, it is produced by fatty acyl-carrier proteins and ethanol, with the help of thioesterase (TesB) and wax synthase (WS) enzymes. One of the foremost barriers in microbial FAEE production is the feedback inhibition of the fatty acid (FA) operon (fabHDG). Here, we studied the effect of biodiesel biosynthesis in E. coli with an engineered fabHDG operon. With a basic FAEE producing BD1 strain harboring tes and ws genes, biodiesel of 32 mg/L were produced. Optimal FAEE biosynthesis was achieved in the BD2 strain that carries an overexpressed operon (fabH, fabD, and fabG genes) and achieved up to 1291 mg/L of biodiesel, a 40-fold rise compared to the BD1 strain. The composition of FAEE obtained from the BD2 strain was 65% (C10:C2, decanoic acid ethyl ester) and 35% (C12:C2, dodecanoic acid ethyl ester). Our findings indicate that overexpression of the native FA operon, along with FAEE biosynthesis enzymes, improved biodiesel biosynthesis in E. coli.

Highlights

Global warming and scarcity of fossil fuel reserves motivate the scientific community to produce alternative biofuels [1,2,3,4,5]
Fatty acid ethyl ester (FAEE), is a potential candidate to substitute diesel fuel [6]. It is obtained by transesterification of ethanol with oil/fats obtained from plants, animals, or microorganisms [7]
2 roef 8cently, E. coli with external thioesterase (TesB) and wax synthase (WS) enzymes produced fatty acid ethyl ester (FAEE) from glucose as a casrubgoanrsstoouprrcoed[u1c0e].reSaodmy-etoa-tutesembpiotsdwieseerle[m9].aWdeiltdhatytpdeeEmscohnesritcrhaitaecdoltihies uFAnaEbEleptroopdruocdtuiocen FinAEE. c. oli by addinHgoewxeovgeern, oreucsenfatltyt,y Ea.cicdosli inwtioththeextceurnltaul rtehmioeesdteiuramse [1(T1e,1sB2)]. aHndowweavxers,ytnhtehaussee(oWf Se)xoegnzeynmouess fatty acid inprtohdeuccuedltuFAreEmE efrdoimumgluisconsoena-seacocnarobmonicsaolu. rTchee[r1e0f]o

Summary

Introduction

Global warming and scarcity of fossil fuel reserves motivate the scientific community to produce alternative biofuels [1,2,3,4,5]. 2 roef 8cently, E. coli with external thioesterase (TesB) and wax synthase (WS) enzymes produced FAEE from glucose as a casrubgoanrsstoouprrcoed[u1c0e].reSaodmy-etoa-tutesembpiotsdwieseerle[m9].aWdeiltdhatytpdeeEmscohnesritcrhaitaecdoltihies uFAnaEbEleptroopdruocdtuiocen FinAEE. FAEE by fatty acid-CoA ligase and wax synthase encoded by fadD and ws genes, respectively [4]. TThhee ccuurrrreenntt pprroodduuccttiioonn yyiieelldd ooff FFAAEEEE iinn bbaacctteerriiaa ddooeess nnoott mmeeeett aa ccoommmmeerrcciiaall tthhrreesshhoolldd..

Results

Conclusion