We investigated new microbial systems for their ability to convert lesquerolic acid (LQA; 14-hydroxy-11(Z)-eicosenoic acid) to value-added products. A strain of Sphingobacterium multivorum (NRRL B-23212) was found previously to convert LQA to 14-oxo-11(Z)-eicosenoic acid (14-OEA) as determined by gas chromatography-mass spectrometry and nuclear magnetic resonance analyses. Conversion of LQA was subsequently extended to examine S. multivorum and closely related species of Pedobacter, Spirosoma, Chryseobacterium, and Flavobacterium. Among 25 of such environmental isolates, a group of bacteria, whose identity was further confirmed by 16S rRNA gene sequence analysis as S. multivorum, was the only species found to conduct LQA conversion to produce 14-OEA. Among these strains, however, NRRL B-14797 was a variant strain devoid of the specific biologic activity. A new culture medium at pH 7.0 was defined to include Fe(2+) and Mn(2+) mineral ions, glycerol, and EDTA.2Na to improve the production of 14-OEA from the initial yields of 2% to 13% to approximately > or =75% for the reactive S. multivorum strains. These S. multivorum strains represent the first group of bacteria reported to carry out the functional modification of LQA.