Production of hydroxy fatty acids from unsaturated fatty acids by Flavobacterium sp. DS5 hydratase, a C‐10 positional‐ and cis unsaturation‐specific enzyme

A new microbial isolate, Flavobacterium sp. DS5, converted oleic and linoleic acids to their corresponding 10‐keto‐and 10‐hydroxy fatty acids. The hydration enzyme seems to be specific to the C‐10 position. Conversion products from α‐ and γ‐linolenic acids were identified by gas chromatography/mass spectrometry, Fourier transform infrared, and nuclear magnetic resonance as 10‐hydroxy‐12( Z ),15( Z )‐octadecadienoic and 10‐hydroxy‐6( Z ),12( Z )‐octadecadienoic acids, respectively. Products from other 9( Z )‐unsaturated fatty acids also were identified as their corresponding 10‐hydroxy‐ and 10‐keto‐fatty acids. Trans unsaturated fatty acid was not converted. From these results, it is concluded that strain DS5 hydratase is indeed a C‐10 positional‐specific and cis ‐specific enzyme. DS5 hydratase prefers an 18‐carbon monounsaturated fatty acid. Among the C 18 unsaturated fatty acids, an additional double bond at either side of the 9,10‐position lowers the enzyme hydration activity. Because hydratases from other microbes also convert 9( Z )‐unsaturated fatty acids to 10‐hydroxy fatty acids, the C‐10 positional specificity of microbial hydratases may be universal.