Characterization of novel methyl-branched chain fatty acids from a halophilic Bacillus species

The 4-methylated fatty acids 4,9-dimethyldecanoic, 4,11-dimethyldodecanoic, 4,10-dimethyldodecanoic, and 4,13-dimethyltetradecanoic acid as well as th e 2-methylated fatty acids 2,13-dimethyltetradecanoic and 2, 12-dimethyltet radecanoic acid were identified for the first time in nature in the halophi lic bacterium Bacillus sp. isolated from the salt pans of Burgas in Bulgari a. The principal fatty acids in this bacterium were a series of iso-anteiso fatty acids with chain lengths between C-11 and C-19, but an interesting s eries of linear alkylbenzene fatty acids with chain lengths between C-10 an d C-14, such as 12-phenyldodecanoic acid, were also identified. The novel 4 -methylated fatty acids were characterized using a combination of GC-MS and chemical transformations such as N-acylpyrrolidide derivatization. The 2-m ethylated fatty acids were also identified by GC-MS and gas chromatographic coelution with synthetic samples. The novel methyl-branched fatty acids pr obably originated from the selective incorporation of methylmalonyl-CoA by one of the fatty acid-synthesizing enzymes of the bacterium.