Biodegradation potentials of polyaromatic hydrocarbon (pyrene and phenanthrene) by Proteus mirabilis isolated from an animal charcoal polluted site

•Animal charcoals pollute agricultural medium with toxic hydrocarbons.•Bacterial strain, Proteus mirabilis 10c was isolated from charcoal polluted sediment.•Strain 10c resisted some antibiotics and utilized some aliphatic and aromatic hydrocarbons for growth.•Excellent biodegradation of pyrene and phenanthrene was achieved with the strain.•The bacterium is a promising biotechnological tool for mitigating sites polluted with animal charcoal.

Indiscriminate disposal of animal charcoal from skin and hides cottage industries often impact the environments with toxic hydrocarbon components and thus require eco-friendly remedial strategies. A bacterial strain isolated from a site polluted with animal charcoal was characterized, identified as Proteus mirabilis 10c, and studied for ability to degrade pyrene and phenanthrene. The bacterium resisted 30 µg chloramphenicol, 10 µg ampicillin, 30 µg amoxicillin and 10 µg perfloxacin; while it utilized a number of polycyclic aromatic hydrocarbons and cinnamic acid. Specific growth rate on pyrene and phenanthrene were 0.281 d−1 and 0.276 d−1, respectively. Kinetics of degradation of pyrene was 87.92 mg l−1 in 30 days at the rate of 2.93 mg l−1 d−1, biodegradation constant at 0.073 d−1 and half-life of 9.50 d. The corresponding values for phenanthrene degradation kinetics by the bacterium were 90.12 mg l−1, 3.02 mg l−1 d−1, 0.079 d−1 and 8.77 d, respectively. Efficient degradation of crude oil (92.3%) in chemically defined medium was evident with near-disappearance of most aromatic spectra in 30 days. Considering its unique physiologies and broad specificities for aromatic and aliphatic hydrocarbons, the bacterium has potentials for decommissioning environments contaminated with toxic components of animal charcoal.