Characteristics of Hydrocarbon Degradation by Bacteria Isolated from Drill Cuttings

The microorganisms Bacillus circulans NSh, B. firmus OBR 1.1, B. firmus OBR 3.1, Solibacillus silvestris OBR 3.2, B. circulans OBR 3.3, Halomonas sp. OBR 1, and Erwinia rhapontici OBR 4.1, isolated from drill cuttings, were shown to be able to degrade oil, mineral oil, and diesel fuel. The B. circulans NSh and B.firmus OBR 1.1 bacteria were shown to degrade 62 and 32% of oil, respectively, in an alkaline medium (pH9) after 14 days and 42 and 22% of oil, respectively, in a saline medium (10% NaCl). Under conditions of increased ambient salinity and alkalinity, the B. circulans NSh and S. silvestris OBR 3.2 bacteria were shown efficiently to degrade petroleum hydrocarbons not only individually, but also in combination with the oil-oxidizing Dietzia maris AM3 microorganism. The efficiency of oil degradation by the consortium composed of B. circulans NSh D. maris AM3 was higher than that by monocultures.