Isolation of a Petroleum-degrading Halo Tolerant Bacterium and Study the Effects of Environmental Factors in Biodegrading for Environmental Protection

Soil and water petroleum pollution threatens living organisms in the environment. This pollution can be removed by an economically cheap and environmentally safe method using bacteria. In this study, a halo tolerant bacterium was isolated from a spring near Dezful in Khuzestan which could effectively degrade petroleum. During growth in a mineral-base medium containing 1 gram per liter of crude oil as the sole carbon source, this strain produced biosurfactants that emulsified oil in the aquatic phase of the medium. The effects of different pH and salinity conditions on petroleum biodegradation were also studied and the minimum amounts of nitrogen and phosphorus sources needed for the optimal degradation of 1-gram crude oil was determined. For obtaining growth curves of bacterium in a mineral-base medium and evaluating oil consumption, both the spectrophotometry (650 nm) method and the Lowry method of total protein determination were performed daily. Results showed that the optimal conditions for petroleum biodegradation were pH 8.5 and a salinity of 0-5 % NaCl. Also, the minimum N and P sources needed for degrading 1 gram crude oil were equal to 292 mg NH4Cl and 36 mg Na2HPO4, respectively.