All-Carbon-Atom Refinery of Oleic Acid into Bifunctional Chemicals Using Artificial Consortia of Escherichia coli Strains

Oxyfunctionalization of renewable oleic acid is an environmentally friendly process for producing C9 bifunctional chemicals, i.e., 9-hydroxynonanoic acid and its derivatives. However, the carbon atom economy of 9-hydroxynonanoic acid is extremely low (50%) due to the unavoidable formation of the unifunctional n-nonanoic acid as a coproduct. In this work, to further enhance the feasibility of its application, we report an artificially designed biocatalytic cascade process for the normalization of n-nonanoic acid into 9-hydroxynonanoic acid, which might be further transformed into other C9 bifunctional chemicals, namely 1,9-nonanedioic acid and 9-aminononanoic acid. This cascaded biocatalysis system was operated using different engineered E. coli consortia composed of the desired cell modules, giving 9-hydroxynonanoic acid, 1,9-nonanedioic acid, and 9-aminononanoic acid, with space-time yields of 3.1, 4.9, and 1.9 g L–1 d–1, respectively. The biocatalytic process developed herein provides a promising pathway for the eco-friendly production of structurally diverse C9 bifunctional chemicals with a 100% carbon atom economy, representing the first examples, to our knowledge, for the valorization of the byproduct (n-nonanoic acid) originated from oleic acid biorefinery.