Isolation and characterization of a novel strain, Bacillus sp KJ629314, with a high potential to aerobically degrade diesel

In this research, a diesel-degrading bacterium (strain KJ629314) was isolated from a mining soil contaminated with total petroleum hydrocarbons (TPH) and properly characterized using the polymerase chain reaction (PCR) molecular technique. The 16s rDNA sequence analysis allowed to identify KJ629314 as a strain of Bacillus sp. Experimental phase was conducted to assess the aerobic biodegradation of diesel; to determine the removal efficiency and the corresponding microbial growth; diesel was used as a substrate - electron donor - carbon source; and oxygen (via aeration) as the electron acceptor. Tests were conducted in microcosms with sterile sand with nutrients according to the Nitrogen:Phosphorus ratio of 15:1 at different diesel concentrations (10,000; 20,000; 30,000; 40,000 and 50,000 mg/kg soil). Results showed that the strain of Bacillus sp KJ629314 has a high potential in the biodegradation of diesel at the evaluated concentrations, and it was demonstrated that the removal efficiency was greater at low concentrations of diesel obtaining higher values for the microbial growth and diesel biodegradation rate constants. These promising results support the fact that Bacillus sp KJ629314 may be used as a novel biological resource to develop a bioprocess for the bioremediation of diesel-contaminated soil.