Production of 10,12-dihydroxy-8(E)-octadecenoic acid, an intermediate in the conversion of ricinoleic acid to 7,10,12-trihydroxy-8(E)-octadecenoic acid by Pseudomonas aeruginosa PR3

A bacterial isolate, Pseudomonas aeruginosa (PR3), has been reported to produce a new compound, 7,10,12-trihydroxy-8(E)-octadecenoic acid (TOD), from ricinoleic acid (Kuo TM, LK Manthey and CT Hou, 1998, J Am Oil Chem Soc 75: 875-879). The reaction is unique in that it involves an introduction of two additional hydroxyl groups at carbon 7 and 10 and a rearrangement of the double bond from carbon 9-10 (cis) to 8-9 (trans), In an effort to elucidate the metabolic pathway involved in the formation of TOD from ricinoleic acid by PR3, we have isolated another compound from the reaction mixture using HPLC. The structure of the new compound was determined to be 10, 12-dihydroxy-8(E)-octadecenoic acid (DHOD) by GC/MS, FTIR, and NMR, The structural similarity between DHOD and TOD and the results from the time course study of the above two compounds strongly suggested that DHOD was an intermediate in the bioconversion of ricinoleic acid to TOD by PR3, The optimum pH and temperature for the production of DHOD from ricinoleic acid by PR3 was 6.5 and 26 degrees C, respectively. This is the first report on the production of 10,12-dihydroxy-8(E)-octadecenoic acid from ricinoleic acid by PR3.