Isolation and molecular characterization of phenol-degrading gram-positive bacteria from oil-contaminated soil

One of the aspects of bioremediation of contaminated site is the isolation and identification of bacterial isolates from polluted soil in order to choose the most active ones. Three phenol-degrading bacteria were isolated from contaminated soil samples using direct isolation method on mineral salt medium supplemented with 2.0 mM phenol as the sole carbon source. In this study, three phenol-degrading bacteria were characterized by morphological, biochemical properties and differentiated by DNA fingerprinting technique using Random amplified polymorphic DNA (RAPD) and specific and random amplification based on PCR (SARA-PCR) analyses. Phenol-degrading bacteria are designated Bacillus sp. PD-02, PD-06 and PD-08. The aerobic isolates grew on phenol at concentrations ranging from 2-16 mM. These isolates are a strictly aerobic, gram-positive, endospore-forming, rod-shaped, catalase positive, oxidase negative and grew at salinities ranging from 0.28 to 10.0% and temperatures ranging from 15 to 41°C. PCR application for detection of catabolic genes involved in phenol degradation showed the presence of catechol 1,2 Dioxygenase (C12DO) and phenol hydroxylase but the fragments of catechol 2,3 Dioxygenase (C23DO), salicylate-1-hydroxylaswe are not detected. The ability of the isolates to degrade phenol make them a potential candidate for use in bioremediation of environments contaminated by such or related compounds.