Biodegradation of Polycyclic Aromatic Hydrocarbons by the Biofilm Forming Bacteria Priestia aryabhattai BMRS3B Isolated from the Rhizosphere of Oryza sativa

Polycyclic aromatic hydrocarbons (PAHs) have already been identified as consistent environmental pollutants with toxic and carcinogenic properties. PAHs contaminants from the environment can ultimately enter into the food chain to result in unpredictable damages to the living system. As the environmental remediation of PAHs has been demonstrated to be mediated by microbial metabolism, characterisation of novel strains with degradative potential is significant. In the current study, naphthalene degrading rhizobacteria were characterised from the rhizospheric soil of paddy fields from Kuttanad, Kerala. From these, the strain Priestia aryabhattai BMRS3B was found to have the ability to degrade naphthalene, phenanthrene, and fluorene within 120 h of reaction. By the Gas Chromatography-Mass Spectrometry (GC–MS) and Fourier Transform Infrared (FTIR) Spectroscopy analyses, formation of degradation products like phthalic acid derivatives, dibutyl phthalate and the presence of several fatty acid methyl esters could be confirmed. These metabolites have formed as a result of oxygenation, dehydrogenation and ring cleavage reactions mediated by the selected strain when cultured in PAH containing media. The degradation pattern was consistent for all the PAHs selected for the study, where the formation of different fatty acid methyl esters indicated the metabolic activity of the selected bacteria. Additionally, Priestia aryabhattai BMRS3B was observed to have enhanced biofilm formation when cultured in the presence of selected PAH, which highlighted its tolerance and potential for bioremediation applications in PAH-contaminated environment.