Microbial synthesis of undec-9-enoic acid, heptyl ester from renewable fatty acids using recombinant Corynebacterium glutamicum-based whole-cell biocatalyst

The conversion of ricinoleic acid from renewable sources to long-chain α,ω-dicarboxylic acids or w-hydroxyl carboxylic acids by microbial processes is constrained by toxicity issues. Here, we demonstrate the possible role of Corynebacterium glutamicum as a new microbial strategy for the biotransformation of fatty acids. The established strain Escherichia coli failed to grow at 5 mM n-heptanoic acid, while the specific growth rate of C. glutamicum declined by 28%. We partially constructed a previously designed multistep biocatalytic pathway in C. glutamicum, and confirmed that the C. glutamicum biocatalyst successfully converted ricinoleic acid to undec-9-enoic acid, heptyl ester via 12-keto-oleic acid. We investigated the effects of cultivation and reaction temperatures, and the type and concentration of non-ionic detergent on recombinant C. glutamicum whole-cell bioconversion. At a cultivation temperature of 30 °C and a reaction temperature of 35 °C, and in the presence of 0.09 g/L Triton X-100, the whole-cell C. glutamicum biocatalyst produced 0.8 mM undec-9-enoic acid, heptyl ester from 1.9 mM 12-ketooleic acid. It also generated 0.7 mM undec-9-enoic acid, heptyl ester from 5.5 mM ricinoleic acid. This is the first report of undec-9-enoic acid, heptyl ester production using a recombinant C. glutamicum-based biocatalyst.