Conversion of oleic acid to 10-ketostearic acid by Sphingobacterium sp strain O22

The conversion of oleic acid by a bacterium, tentatively identified as Sphingobacterium thalpophilum strain O22, was investigated. The microorganism was isolated as a stable culture from compost that was enriched with soybean oil outdoors and subsequently with oleic acid in the laboratory: Strain O22 converted oleic acid to products identified as 10-ketostearic acid (95% of the total conversion product) and 10-hydroxystearic acid (5%). This is in contrast to S. thalpophilum strain B-14797, which produces solely 10-hydroxystearic acid. Maximal conversion was reached in about 36 h after the addition of oleic acid to the fermentation broth. The yield of 10-ketostearic acid was approximately 75% from 0.26 g of oleic acid in 30 mL fermentation broth at 28 degrees C and 200 rpm for 48 h. This is the first report on the major production of 10-ketostearic acid by a microorganism in the genus Sphingobacterium.