EFFECT OF CRUDE OIL ON MICROBIAL PROCESSES IN MARINE SEDIMENTS
ABSTRACT Studies were carried out to detect and quantitate 12 microbial processes occurring in sediments in the north central Gulf of Mexico, and to determine the impact of low-level concentrations of oil on these processes. Under the simulated in situ conditions employed, photosynthesis, nitrification, dentrification, nitrogen fixation, sulfate reduction, and phosphate uptake were minimal, while sulfur oxidation and catabolic carbonaceous processes (heterotrophic activity, lipolysis, proteolysis cellulolysis, and chitinolysis) were present with varying degrees of activity. Little difference in metabolic activity was detected between oil-production platform sites and corresponding control sites, among different sediment types, or among three sampling seasons, and the presence of oil at up to 200 microliter per milliliter sediment had no significant impact on reaction rates. Pure culture studies confirmed that low-level concentrations of crude oil had essentially no effect on these processes.