OCCURRENCE AND SIGNIFICANCE OF LONG-CHAIN (OMEGA-1)-HYDROXY FATTY-ACIDS IN METHANE-UTILIZING BACTERIA

The cell residue derived (H+-labile lipid) hydroxy fatty acid composition of 16 strains of methane-utilizing (methanotrophic) bacteria have been analysed as part of a larger program which is investigating the taxonomy and potential uses of these bacteria. The hydroxy fatty acid compositions were determined by GC and GC-MS. Of the 16 strains, 5 strains including Methylosinus sporium UQM3306, Methylocystis parvus UQM3309 and Methylocystis minimus UQM3497 were found to contain long-chain (C26, C28 and C31) (omega-1)-hydroxy fatty acids. The total concentration of (omega-1)-hydroxy fatty acids varied between 65 and 500 ng/g. Although only a limited number of species have been analysed to date, a number of differences were apparent when comparing the (omega-1)-hydroxy acid profiles. The type II methanotrophic bacteria generally contained higher relative concentrations of the (omega-1)-hydroxy acids than found in the type I methanotrophs. These differences may prove to be useful in taxonomic, environmental and organic geochemical investigations.