Bioremediation of petroleum contaminated soils by lipopeptide producing Bacillus subtilis SE1

Hydrocarbons released into ecosystems have led to environmental pollution and generated a serious threat to human health. Bioremediation is an effective method to break down hazardous hydrophobic environmental contaminants with avoiding economic and technical disadvantages. This study aimed to evaluate the efficiency of Bacillus subtilis SE1, a lipopeptide biosurfactant producer isolated from a petrochemical contaminated soil, on biodegradation of gasoline, diesel oil, crude oil and used engine oil in soil microcosms. During 35-day incubation, numbers of soil bacteria in petrochemical contaminated soils with B. subtilis SE1 addition significantly (P < 0.05) increased in comparison with the oil-free soils. Bioaugmentation of SE1 strain also produced a significant (P < 0.05) increase in percent reduction of total phenolic content in oil-polluted soils as compared to the control soils at the end of experiment. This study indicates that B. subtilis SE1 can be a promising hydrocarbon degrader for in situ bioremediation of soil environment polluted with petroleum and petrochemical products. Key words: Bacillus subtilis, biodegradation, bioremediation, gasoline, diesel, crude oil, engine oil.