Screening for omega(-1)-hydroxy fatty acid over-producing mutants for bioconversion of oleic acid by combining general mutagenesis and specific selection

Chemical mutation of a strain producing hydroxy-fatty acid from oleic acid (OA) using NTG (N-methyl-N'-nitro-N-nitrosoguanidine) resulted in a high percentage of improved mutants. A positive screening procedure yielded several high producers, specifically the strain Bacillus pumilus M-F641 (BP M-F641). This strain produced predominantly omega(-1)-hydroxy fatty acid and could utilize higher concentrations of OA than the parent strain. In shake flask culture, the best omega(-1)-hydroxy fatty acid concentration and yield (the ratio of omega(-1)-hydroxy fatty acid accumulation to OA consumption) reached 570 mg L-1 and 11.5%, respectively. Repeated tests showed that the mutant BP M-F641 was genetically stable.