Bioconversion of C20- and C22-polyunsaturated fatty acids into 9S,15S- and 11S,17S-dihydroxy fatty acids by Escherichia coli expressing double-oxygenating 9S-lipoxygenase from Sphingopyxis macrogoltabida

Abstract

Double-oxygenating lipoxygenase (LOX) converted C20- and C22-polyunsaturated fatty acids (PUFAs) into C20 dihydroxy fatty acids (DiHFAs) as inflammatory mediators and C22 DiHFAs as specialized pro-resolving mediators, which are involved in the resolution of inflammation and infection in humans, and their isomers, respectively. However, the quantitative bioconversion of C20- and C22-PUFAs into 9S,15S- and 11S,17S-DiHFAs has been not attempted to date, respectively. Here, we performed the efficient quantitative production of 9S,15S- and 11S,17S-DiHFAs by Escherichia coli expressing 9S-LOX from Sphingopyxis macrogoltabida. The optimal bioconversion conditions of the C20 PUFA arachidonic acid or the C22-PUFA docosahexaenoic acid were pH 8.5, 35°C, 6mM substrate, and 5g dry cells/L for C20 PUFAs or 7g dry cells/L for C22-PUFAs, respectively. Under these conditions, E.coli expressing double-oxygenating 9S-LOX from S.macrogoltabida converted arachidonic acid, eicosapentaenoic acid, docosapentaenoic acidn-3, and docosahexaenoic acid into 5.85mM 9S,15S-dihydroxyeicosatetraenoic acid, 5.79mM 9S,15S-dihydroxyeicosapentaenoic acid, 5.89mM 11S,17S-hydroxydocosapentaenoic acidn-3, and 5.24mM 11S,17S-dihydroxydocosahexaenoic acid in 40, 30, 50, and 60min, with conversion yields of 97.5%, 96.5%, 98.1%, and 87.3%; and volumetric productivities of 8.78, 11.6, 7.07, and 5.24mM/h, respectively. To date, these are the highest concentrations, conversion yields, and volumetric productivities reported in the bioconversion of C20- and C22-PUFAs into DiHFAs.