Evolutionary Relationship of Polycyclic Aromatic Hydrocarbons Degrading Bacteria with Strains Isolated from Petroleum Contaminated Soil Based on 16S rRNA Diversity

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants, ubiquitously present and are hazardous to all forms of life due to their toxic, carcinogenic, and mutagenic nature. With enhanced understanding of adverse effects of PAHs on living organisms, reclamation of PAH-contaminated sites has become a global concern. In order to devise efficient bioremediation strategies for PAH-degradation, the identification and study of metabolic potential of microbial species is essential. The goal of this study is to isolate PAH-degrading bacterial strains from petroleum contaminated soil that can utilize PAHs as their sole carbon source and investigate their growth on medium containing PAHs as only carbon source. For the first time, the evolutionary relationship of isolated bacterial strains with known PAH-degrading bacterial strains having PAH-catabolic genes/enzymes involved in PAH-bioremediation was examined. Two strains isolated from contaminated soil, that is, Kocuria flava DTU-1Y and Rhodococcus pyridinivorans DTU-7P may have the ability to utilize PAHs as sole carbon source for their growth. Phylogenetic analysis for evolutionary relationship revealed that these strains are related to different known PAH-degrading bacterial strains which have catabolic genes/enzymes involved in degradation pathway. The bacterial strains reported in this study may also possess the genes responsible for PAH-degradation and can prove useful in devising sustainable bioremediation approach.

KEYWORD:

• Bioremediation
• evolutionary relationship
• microorganisms
• PAHs

Acknowledgments

The authors acknowledge the help of Bharat Petroleum Corporation Ltd. (BPCL), Bijwasan Delhi for providing the samples of contaminated soil; and CSIR-Institute of Microbial Technology, Chandigarh (IMTECH), India, for 16S rRNA sequencing.