Biodegradation potential of petroleum hydrocarbons by bacteria and mixed bacterial consortium isolated from contaminated sites

The aim of this study was to isolate, characterize, and evaluate the potential of petroleum hydrocarbon (PHC)-degrading bacterial strains from oil-contaminated soil in the Meerut region. Among 59 oil-degrading bacterial cultures isolated from the oil-contaminated soil samples, 1 Bacillus species, 2 species of Pseudomonas, and 1 species of Micrococcus, identified on the basis of biochemical and 16s rDNA sequencing, were found to have the ability to utilize PHCs such as benzene, diesel, toluene, anthracene, and naphthalene. These strains were selected for further study to measure the quantitative determination of PHC metabolization. Along with these selected strains, a mixed bacterial consortium was formulated and used for PHC degradation. Among the individual strains, Pseudomonas sp. APHP9 performed better than the other bacterial isolates. Maximum biodegradation of benzene and toluene was done by the bacterial consortium. The mean growth rate constant (K) of soil isolates also increased with a successive increase in PHC concentration. Moreover, Bacillus sp. APHP6, Pseudomonas sp. APHP9, Pseudomonas sp. APBP1, Micrococcus sp. APIO4, and the consortium resulted in a 54.8%, 60.2%, 40.9%, 32.5%, and 66.2% decrease in benzene concentration and a 61.2%, 68.4%, 53.7%, 39.3%, and 75.4% decrease in diesel concentration, respectively, after 6 days of incubation as estimated by HPLC analysis.