Microbial degradation of crude oil in marine environments tested in a flask experiment

Thirteen different bioremediation products were evaluated for their effectiveness in biodegrading petroleum hydrocarbons. All 13 products tested in this experiment were listed on the NCP product schedule. Of these 13 products, 12 were bioaugmentation agents and one was a biostimulation agent. All the products were tested for toxicity levels initially, using standardized protocols. The products were sampled and analyzed three times over a 28-day period for most-probable number (MPN) of hydrocarbon degraders and total petroleum hydrocarbon as separate fractions. A subsample was analyzed for MPN, and the rest of the sample was extracted and fractionated in total saturated petroleum hydrocarbons (TsPH) and total aromatic petroleum hydrocarbons (TarPH). This experiment revealed that the petroleum hydrocarbons were biodegraded to an extent significantly greater than that achieved by the naturally occurring microorganisms. After 28 days, some products reduced the TsPH fraction to 60% of its initial weight and the TarPH fraction to 65%. Three of the 13 products tested enhanced microbial degradation of the petroleum to a degree significantly better than the nutrient control treatments. Of these three products, only one showed a toxicity level below that of the control treatment. (C) 1997 Elsevier Science Ltd.