Molecular and functional analysis of naphthalene‐degrading bacteria isolated from the effluents of indigenous tanneries

Abstract

During present study, four naphthalene‐ metabolizing bacteria were isolated from tanneries effluents through enrichment on naphthalene as sole carbon source in minimal salt medium. The bacteria were analyzed to document growth pattern, naphthalene removal efficiency, biochemical and molecular characteristics, antibiotic sensitivity, and metabolic profile. The 16S ribosomal RNA gene sequences were compared through BLAST (basic local alignment search tool) similarity search tool and three isolates were found homologous to Brevibacillus agri strain NBRC 15538 and one similar to Burkholderia lata strain 383. The naphthalene removal efficiencies ranged from 1.16 ± 0.056 mg/h (IUBN1) to 1.379 ± 0.021 mg/h (IUBN26). All isolates were positive for p‐nitrophenyl phosphate (PO4), esculin, and inulin fermentation tests. Majority were positive for glucosaminidase (IUBN3, 17, and 26) and a few for mannitol and sorbitol fermentation (IUBN1). Identification of metabolites through gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry analysis allowed tracing pathways associated with naphthalene degradation. Intermediates such as cis‐dihydrodiolnaphthalene, 2‐hydroxychromene‐2‐carboxylate, 6‐hydroxyhexanoic acid, acetyl‐CoA confirmed that the present study bacteria can metabolize naphthalene through a pathway which differs from the pathways reported in earlier known bacteria. Due to fast growth rates, high naphthalene removal potentials, and multiple degradation pathways, these bacteria can be exploited for bioremediation of naphthalene.

Molecular and metabolic characterization of petroleum hydrocarbons degrading Bacillus cereus

“…1 109 (Reiner 1971;Denome et al 1993;Goyal and Zylstra 1997;Abu Laban et al 2010;Brzeszcz and Kaszycki 2018;Di Canito et al 2018;Muccee et al 2021). Despite the significant contribution to TPH degradation, bioremediation also has limitations, such as less contaminant bioavailability and the production of more toxic compounds (Sharma 2020;Kumar et al 2022).…”

“…and, Falsochrobactrum tianjinense , respectively ( Hu et al 2022 ; Wang et al 2023 ). Additionally, petroleum aromatic compounds degradation mechanisms have also been reported in literature like o-ring cleavage and m-ring cleavage pathways, toluene 4-monooxygenase pathway (TMO), toluene 3-monooxygenase pathway (Tbu), toluene 2-monooxygenase pathway (TOM), toluene dioxygenase pathway (Tod), toluene methyl monooxygenase pathway (TOL) for toluene, salicylate pathway, gentisate pathway, procatechuic acid pathways for naphthalene, anaerobic benzene degradation pathways via methylation, hydroxylation and carboxylation, xylene degradation pathways via phenol hydroxylase, monooxygenase and dioxygenase routes, β-ketoadipic acid pathway of benzoic acid degradation and the novel pathways of toluene and naphthalene degradation involving the cyclohexene, cyclohexane, cyclohexanol and cyclohexanone formation ( Reiner 1971 ; Denome et al 1993 ; Goyal and Zylstra 1997 ; Abu Laban et al 2010 ; Brzeszcz and Kaszycki 2018 ; Di Canito et al 2018 ; Muccee et al 2019 ; Muccee et al 2021 ). Despite the significant contribution to TPH degradation, bioremediation also has limitations, such as less contaminant bioavailability and the production of more toxic compounds ( Sharma 2020 ; Kumar et al 2022 ).…”