Application of bacterial biosurfactants for enhanced removal and biodegradation of diesel oil in soil using a newly isolated consortium

One of the major environmental problems today is hydrocarbon contamination resulting from the activities related to the petrochemical industry. Bioremediation, involving the use of microorganisms to detoxify or remove pollutants is the most interesting strategy for hydrocarbon contamination depollution. In this aim, diesel oil biodegradation in soil was studied by four hydrocarbon degrading bacteria. A lipopeptide biosurfactant produced by Bacillus subtilis SPB1, confirmed to increase diesel mobility, was tested to increase diesel biodegradation along with co-inoculation with two biosurfactant producing strains. Culture studies revealed the enhancement of diesel biodegradation by the selected consortium with the addition of SPB1 lipopeptide and in the cases of co-inoculation by biosurfactant producing strain. In fact, an improvement of about 12.19% and 15.35% of diesel degradation were registered in the presence of 0.1% lipopeptide biosurfactant and when culturing B. subtilis SPB1 strain with the isolated consortium, respectively. Furthermore, the best improvement; evaluated to about 32.67% for soil contaminated with diesel was recorded when using the consortium cultured with B. subtilis SPB1 and Acinetobacter radioresistens RI7 strains. Gas phase chromatography analyses were correlated with the gravimetric evaluation of the residual hydrocarbons. Results suggested the potential applicability of the selected consortium along with the ex-situ and in-situ added biosurfactant for the bioremediation of diesel contaminated water and soil.