Simultaneous Enzyme/Whole-Cell Biotransformation of Plant Oils into C9 Carboxylic Acids

Abstract

Oxyfunctionalization of plant oils such as olive oil and soybean oil into C9 carboxylic acids (e.g., n-nonanoic acid and 9-hydroxynonanoic acid) was investigated. The biotransformation was composed of hydrolysis of plant oils by the Thermomyces lanuginostis lipase (TLL) and C9-C10 double-bond cleavage in unsaturated fatty acids by a serial reaction of a fatty acid double bond-hydratase of Stenotrophomonas maltophilia, an alcohol dehydrogenase of Micrococcus luteus, and a Baeyer-Villiger monooxygenase (BVMO) of Pseudomonas putida KT2440 expressed in Escherichia coli. The newly cloned oleate hydratase allowed one to produce 10-hydroxyoctadecanoic acid and 10-hydroxyoctadec-12-enoic acid at a high rate from oleic acid and linoleic acid, respectively, which are major fatty acid constituents of many plant oils. Furthermore, overexpression of a long chain fatty acid transporter FadL in the recombinant E. coli led to a significant increase of whole-cell biotransformation rates of oleic acid and linoleic acid into the corresponding esters. The resulting esters (the BVMO reaction products) were hydrolyzed in situ by TLL, generating nonanoic acid, non-3-enoic acid, and 9-hydroxynonanoic acid, which can be further oxidized to 1,9-nonanedioic acid. This study demonstrated that industrially relevant C9 carboxylic acids could be produced from olive oil or soybean oil by simultaneous enzyme/whole-cell biocatalysis.