Mixed polyaromatic hydrocarbon degradation by halotolerant bacterial strains from marine environment and its metabolic pathway

Abstract

Accidents involving diesel oil spills are prevalent in sea- and coastal regions. Polycyclic aromatic hydrocarbons (PAHs) can be adsorbed in soil and constitute a persistent contaminant due to their poor water solubility and complex breakdown. PAHs pollution is a pervasive environmental concern that poses serious risks to human life and ecosystems. Thus, it is the need of the hour to degrade and decontaminate the toxic pollutant to save the environment. Among all the available techniques, microbial degradation of the PAHs is proving to be greatly beneficial and effective. Bioremediation overcomes the drawbacks of most physicochemical procedures by eliminating numerous organic pollutants at a lower cost in ambient circumstances and has therefore become a prominent remedial option for pollutant removal, including PAHs. In the present study, we have studied the degradation of Low molecular Weight and High Molecular Weight PAH in combination by bacterial strains isolated from a marine environment. Optimum pH, temperature, carbon, and nitrogen sources, NaCl concentrations were found for efficient degradation using the isolated bacterial strains. At 250 mg/L concentration of the PAH mixture an 89.5% degradation was observed. Vibrio algiolytcus strains were found to be potent halotolerant bacteria to degrade complex PAH into less toxic simple molecules. GC-MS and FTIR data were used to probe the pathway of degradation of PAH.