Isolation and Characterization of an E. coli Mutant Strain Growing Well on Nonanoic Acid and Producing Azelaic Acid

Abstract

Dicarboxylic acids (DCAs) are useful building blocks for compounds such as polyesters, nylons, and plastics as well as medications. Their industrial applications depend on carbon chain length. Recently, medium-chain DCA has been in more spotlight than short- and long-chain DCA. The chemocatalytic production of dicarboxylic acids is limited by production of unwanted by-products. Here, we report an Escherichia coli mutant strain that has the potential for the mass production of medium-chain DCA. Wild-type E. coli MG1655 cannot grow on nonanoic acid (C9 fatty acid) probably because of their toxicity and inactive metabolism. We obtained an E. coli strain that can grow faster than the wild type on nonanoic acid by evolutionary engineering and analyzed mutations that enable to utilize nonanoic acid by whole-genome sequencing. Then enzyme system AlkBGT on the alk operon from Pseudomonas putida GPo1 which can efficiently ω-functionalize shortand medium-chain fatty acids and produce hydroxy fatty acid was expressed in the evolutionary engineered strain to produce the azelaic acid (C9 DCA). The mutant strain showed approximately 3-fold increased production of azelaic acid in comparison with wild type strain.