Effects of petroleum hydrocarbons on the phospholipid fatty acid composition of a consortium composed of marine hydrocarbon-degrading bacteria

Phospholipid ester-linked fatty acids (PLFAs) of a bacteria consortium, reconstituted in vitrofrom ten marine hydrocarbon-degrading bacteria, were studied. Culture of the consortium with ammonium acetate as the sole carbon source mainly yielded even-numbered PLFAs composed of straight chain saturated (ca. 26%) and monounsaturated (ca. 71%) fatty acids. Growth of the consortium on Blend Arabian Light petroleum (BAL 250) resulted in a complex PLFA profile with the appearance of (1) odd-numbered straight chain PLFAs, mainly 15:0 and 17:0, (2) iso- and anteiso-PLFAs with 15–17 carbon atoms, (3) 10-, 11-, 12- and 13-monomethylated PLFAs with 16–19 carbon atoms and (4) odd-numbered monounsaturated PLFAs, mainly 17:1 Δ9Zand 19:1 Δ10. When petroleum grown cells were transferred into a medium containing ammonium acetate, the consortium exhibited mainly even-numbered PLFAs: this demonstrated the ability of bacterial strains to restore their PLFA compositions after exposure to petroleum hydrocarbons. It, therefore, appears that the PLFA compositions of these bacteria are strongly influenced by the carbon sources so that several potential biomarkers of hydrocarbon-degrading bacterial activities could be recognized. In addition, an hydrocarbon-degrading activity index (HDAI) was derived from the characteristic PLFA profiles of the consortium grown on ammonium acetate and petroleum hydrocarbons. The HDAI may prove to be a tool revealing the development of hydrocarbon-degrading strains in oil-contaminated sediments.