Increasing Product Tolerance through Metabolic Engineering: Short-Chain Fatty Acids

As we aim to increase the number of fuels and chemicals produced by biocatalysts in an economically competitive process, biocatalyst inhibition by these products becomes an ever-increasing problem. Here we discuss our strategy to increase the tolerance of Escherichia coli to short-chain fatty acids. Our approach is two-pronged: analysis of the inhibition response were used to understand the mechanism of fatty-acid mediated growth inhibition in the wild-type strain, while directed evolution and reverse engineering of a fatty-acid tolerant mutant identifies additional mechanisms of fatty acid tolerance. Analysis methods include transcriptome analysis, lipid profile characterization, membrane fluidity, and intracellular pH measurements.