Engineering Escherichia coli for odd straight medium chain free fatty acid production

Abstract

Microbial biosynthesis of free fatty acids (FFAs) can be achieved by introducing an acyl-acyl carrier protein thioesterase gene into Escherichia coli. The engineered E. coli usually produced even chain FFAs. In this study, propionyl-CoA synthetase (prpE) from Salmonella enterica was overexpressed in two efficient even chain FFAs producers, ML103 (pXZM12) carrying the acyl-ACP thioesterase gene from Umbellularia californica and ML103 (pXZ18) carrying the acyl-ACP thioesterase gene from Ricinus communis combined with supplement of extracellular propionate. With these metabolically engineered E. coli, the odd straight chain FFAs, undecanoic acid (C11:0), tridecanoic acid (C13:0), and pentadecanoic acid (C15:0) were produced from glucose and propionate. The highest total odd straight chain FFAs produced by ML103 (pXZM12, pBAD-prpE) reached 276 mg/l with a ratio of 23.43 % of the total FFAs. In ML103 (pXZ18, pBAD-prpE), the highest total odd straight chain FFAs accumulated to 297 mg/l, and the ratio reached 17.68 % of the total FFAs. Due to the different substrate specificity of the acyl-ACP thioesterases, the major odd straight chain FFA components of ML103 (pXZM12, pBAD-prpE) were undecanoic acid and tridecanoic acid, while the ML103 (pXZ18, pBAD-prpE) preferred pentadecanoic acid.

Optimization of odd chain fatty acid production by Yarrowia lipolytica

“…It is reported that exogenous propionate (C3) can be used as a primer for synthesis of odd chain fatty acids: Propionate can be converted to propionyl-CoA by propionyl-CoA synthase, and propionyl-CoA is condensed with malonyl-CoA in the first step of odd chain fatty acid synthesis [ 15 ]. A metabolic engineering strategy with propionate supplementation achieved a production of 0.276 g/L odd chain free fatty acids in E. coli [ 16 ]. In addition, further engineering of E. coli showed an increased percentage of odd chain free fatty acids in total free fatty acids by 6.25-fold with propionate supplementation [ 17 ].…”

Current Challenges and Opportunities in Non-native Chemical Production by Engineered Yeasts

“…By supplying endogenous propionyl-CoA from oxaloacetate through a newly introduced synthetic pathway, the engineered strain with the genetic background for high lipid production was able to produce OCFAs without the supplementation of propionic acid (Park et al, 2020; Figure 4B). In E. coli, the overexpression of propionyl-CoA synthase from Salmonella enterica and acyl-ACP thioesterase from Ricinus communis and Umberllularia california enabled the production of 276 mg/L of OCFAs, with chain lengths of C11-C15, comparable to that in Y. lipolytica, in the presence of optimized propionate supplementation (Wu and San, 2014).…”

“…development of yeast cell factories. Interestingly, unconventional carbon sources other than glucose, such as xylose, acetate, and propionic acid, have been shown to better support metabolic flux through the biosynthesis pathway for non-native chemicals (Wu and San, 2014;Li et al, 2017;Portugal-Nunes et al, 2017;Wu et al, 2019). Thus, non-native chemical production by the engineered yeast strains with non-native carbon metabolism could offer better promises for industrial-scale production of non-native chemicals.…”

De novo Biosynthesis of Odd-Chain Fatty Acids in Yarrowia lipolytica Enabled by Modular Pathway Engineering

“…However, most microorganisms require the presence of propionate in the medium to produce odd-chain FAs. Wu and San have shown that E. coli can produce odd-chain FAs-namely undecanoic acid (C11:0), tridecanoic acid (C13:0), and pentadecanoic acid (C15:0)-if grown with propionatesupplemented medium (Wu and San, 2014). They introduced a propionyl-CoA synthetase (prpE) from Salmonella enterica and acyl-ACP thioesterases (TEs) from Umbellularia californica and FIGURE 1 | Lipid synthesis in Y. lipolytica.…”