Through the screening of about 300 strains of lactic acid bacteria, Pediococcus sp. AKU 1080 was selected as a strain with the ability to hydrate linoleic acid (cis-9,cis-12-octadecadienoic acid) to three hydroxy fatty acids, i.e., 10-hydroxy-cis-12-octadecenoic acid, 13-hydroxy-cis-9-octadecenoic acid, and 10,13-dihydroxyoctadecanoic acid. The strain hydrated one of two cis double bonds at Δ9 and Δ12 positions to produce 10-hydroxy-cis-12-octadecenoic acid and 13-hydroxy-cis-9-octadecenoic acid, respectively, then further hydrated these two mono-hydroxy fatty acids to 10,13-dihydroxyoctadecanoic acid. The growing cells of this strain were applied to the production of 13-hydroxy-cis-9-octadecenoic acid, that is potential as polymer substrates and functional foods but its specific and efficient production was not established. Under the optimum conditions, 2.3 mg/mL of 13-hydroxy-cis-9-octadecenoic acid was produced from 12.3 mg/mL of linoleic acid with 0.04 mg/mL 10-hydroxy-cis-12-octadecenoic acid (HYA) and 0.05 mg/mL 10,13-dihydroxyoctadecanoic acid in the cultivation medium. Specific production of 13-hydroxy-cis-9-octadecenoic acid was attained using cell-free extracts of the strain as the catalyst. Under the optimum conditions, 0.4 mg/mL of 13-hydroxy-cis-9-octadecenoic acid was produced from 2.0 mg/mL of linoleic acid without HYA and 10,13-dihydroxyoctadecanoic acid.
Practical applications: Hydroxy fatty acids are useful as starting materials for industrial chemicals, functional foods, and pharmaceuticals. Regioselective introduction of hydroxyl group to unsaturated fatty acids by microorganisms was applied to hydroxy fatty acid production. Especially, specific production of 13-hydroxy-cis-9-octadecenoic acid, which is useful for the production of 13-oxo-fatty acids with anti-obesity activity, was established in this work.