Abstract
Polycyclic Aromatic Hydrocarbons (PAHs) are hazardous organic pollutants known for their extreme toxic implications to living beings. Their potential carcinogenicity is the major problem related to hydrocarbon contamination. The development of efficient remedy for its removal remains a challenge. Microbial degradation represents an eco-sustainable strategy to detoxify these persistent pollutants. This study employs a novel and combined approach of metabolomic and genomic (whole genome sequencing) analyses to elucidate the mechanisms involved in the biodegradation of naphthalene, phenanthrene and fluorene by Priestia aryabhattai BMRS3B. Remarkably, BMRS3B sustains its growth and efficiently utilised naphthalene, phenanthrene and fluorene at concentrations up to 100 mgmL⁻1, highlighting its high tolerance and utilisation efficiency. The strain achieved a maximum biodegradation of the selected PAHs-naphthalene, phenanthrene and fluorene and this was evidently supported with thin layer chromatography, UV spectroscopy along with Gas Chromatography Mass Spectrometry analysis. This revealed that the strain BMRS3B completely degraded naphthalene, phenanthrene and fluorene over 72-120 h, with phthalic acid esters, dibutyl phthalate, 1,2 dibenzenedicarboxylic, bis-3,5,5-trimethylhexylpthalate and didecan-2-yl phthalate identified as the principal intermediates. Moreover, the whole genomic analysis revealed genes encoding ring-cleaving dioxygenases, catechol 2, 3-dioxygenase, cytochromes P450 monooxygenases which are instrumental in bringing aromatic ring catabolism. Finally, a pathway for biodegradation of naphthalene, phenanthrene and fluorene by the selected isolate was proposed on the basis of metabolomic and genomic profiling. These findings place the strain P. aryabhattai BMRS3B as a promising candidate for the bioremediation of PAHs in the contaminated sites.