Degradation of diesel oil in a polluted soil using Bacillus subtilis

Diesel oil, left standing in a laboratory for six months, was used as source for the isolation of Bacillus subtilis, Bacillus cereus, Trichoderma harzanium and Trichothercium roseum. These organisms were found to be hydrocarbon degraders. On further testing, it was found that B. subtilis had higher potential to utilize diesel oil as carbon source. Soil samples were polluted with diesel oil at a loading rate of 5% (v/w) (oil/soil). These soil samples, together with the unpolluted control samples, were seeded with the B. subtilis isolate. The degradation of the diesel oil was monitored over a twenty-seven -day period, using gravimetric method. The rates of degradation of diesel oil by the isolate at the end of day one, day twelve and day twenty-seven were 5.8 x 10(-4), 1.83 x 10(-3) and 1.05 x 10(-3) g/h, respectively.