Petroleum Biodegradation by Two Mycobacterium Isolates from Persian Gulf

The effects of nitrogen (N) and phosphate (P) concentrations and temperature on crude oil biodegradation by two bacterial strains PG01 and PG02, previously isolated from Persian Gulf, were assessed. In order to determine the optimum concentration of N and P sources and temperature for oil consumption by the isolates, bacteria were cultured in 100 ml agitating culture flasks containing mineral salt medium with 1 gram crude oil as sole carbon source. Measurements of total protein, as an indicator of petroleum biodegradation, revealed that the optimum N and P concentrations for oil consumption by strain PG01 are equal to 0.146 gram ammonium chloride and 0.024 gram di-sodium hydrogen phosphate per gram crude oil. The other strain, PG02, needed more N source for optimum growth and the results were 0.195 gram ammonium chloride and 0.024 gram di-sodium hydrogen phosphate per gram crude oil. Both isolates had maximum oil consumption at 35 degree centigrade. Gravimetric analysis showed that PG01 and PG02 strains respectively mineralized 70.81% and 83.94% crude oil during the 5 day period of incubation. When the mixture of two strains was used higher results were achieved (87.61%). Characterization tests and determination of guanine + cytosine content of DNA showed that both isolates have maximum similarity to Mycobacterium obuense.