ANAEROBIC BIODEGRADATION OF LONG-CHAIN N-ALKANES UNDER SULFATE-REDUCING CONDITIONS

The ability of anaerobic microorganisms to degrade a wide variety of c rude oil components was investigated using chronically hydrocarbon-con taminated marine sediments as the source of inoculum. When sulfate red uction was the predominant electron-accepting process, gas chromatogra phic analysis revealed almost complete n-alkane removal (C-15-C-34) fr om a weathered oil within 201 d of incubation. No alteration of the oi l was detected in sterile control incubations or when nitrate served a s an alternate electron acceptor. The amount of sulfate reduced in the oil-amended nonsterile incubations was more than enough to account fo r the complete mineralization of the n-alkane fraction of the oil; no loss of this anion was observed in sterile control incubations, The mi neralization of the alkanes was confirmed using C-14-14,15-octacosane (C28H58), With 97% of the radioactivity recovered as (CO2)-C-14. These findings extend the range of hydrocarbons known to be amenable to ana erobic biodegradation. Moreover, the rapid and extensive alteration in the n-alkanes can no longer be considered a defining characteristic o f aerobic oil biodegradation processes alone.