Isolation and characterization of four polycyclic aromatic hydrocarbon degrading bacteria from soil near an oil refinery

Four bacterial strains (I-IV) capable of optimum growth on 0.1% naphthalene, anthracene or a mixture of naphthalene and phenanthrene were isolated from soil near an oil refinery. Two isolates (I and II) were identified as belonging to the genus Micrococcus, while strains III and IV were identified as Pseudomonas and Alcaligenes respectively. All the isolates were found to bear high molecular weight plasmid DNA (isolate I and IV 89%, II 67.5% and III 92.1% of lambda DNA), which is presumed to aid in the metabolism of polycyclic aromatic hydrocarbons. The strains also showed appreciable growth at high concentrations of NaCl (up to 7.5%).