Is strain DS5 hydratase a C-10 positional specific enzyme? Identification of bioconversion products from α- and γ-linolenic acids byFlavobacterium sp. DS5

Abstract

Previously, we reported the isolation of a new microbial strain,Flavobacterium sp. DS5 (NRRL B-14859) which converted oleic and linoleic acids to their corresponding 10-keto- and 10--ydroxy-fatty acids. The hydration enzyme seemed to be specific to the C-10 position. Now we have identified, by GC/MS, NMR, and FTIR, the bioconversion products from α-linolenic acid as 10-hydroxy-12(Z), 15(Z)-octadecadienoic acid and from γ-linolenic acid as 10-hydroxy-6(Z), 12(Z)-octadecadienoic acid. Products from 9(E)-unsaturated fatty acids were also identified as their corresponding 10-hydroxy or 10-keto fatty acids. From these results, it is concluded that strain DS5 hydratase is indeed a C-10 positional-specific enzyme and prefers an 18-carbon mono-unsaturated fatty acid. Among the C18 unsaturated fatty acids, an additional double bond on either side of the C-9 position lowers the enzyme hydration activity.