MICROBIAL DEGRADATION OF NAPHTHALENE THROUGH BACILLUS CEREUS RD6 ISOLATED FROM REFINERY OIL SLUDGERUBY DOLEY AND MANOJ BARTHAKURAbstract Oil contains a number of hydrocarbons. It is a complex mixture of linear, branched and cyclic alkanes, and mono- and polyaromatic compounds like benzene, toluene, xylene, ethylbenzene, naphthalene etc. These compounds are of utmost concern to human health because of their genotoxic, mutagenic and carcinogenic effects. Naphthalene is a common polycyclic aromatic hydrocarbon (PAH) and has been considered as a model for microbial degradation study. The aim of this study was to evaluate the naphthalene degradability by indigenous bacterial strain isolated from oil sludge. Twelve bacterial isolates were obtained from the oil sludge of Guwahati Refinery, Assam, India and after preliminary screening the isolate designated as RD6 was considered for degradation study of naphthalene. The isolate was further identified as Bacillus cereus through biochemical tests and molecular characterization by 16SrDNA gene sequencing. Phylogenetic tree was constructed with BLAST result of closely related sequences using MEGA 7 software. The sequence of Bacillus cereus RD6 (MH114968) was submitted to NCBI gene bank for global retrieval. Detection of eight metabolic biomarkers such as oxalic acid, dibutyl phthalate, 1,2- benzene dicarboxylic acid, fumaric acid, 2-propenoic acid, phthalic acid, Benzoic acid, and Eicosane in GC-MS analysis reveals the degradation of naphthalene by Bacillus cereus RD6. |