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Polycyclic aromatic hydrocarbons (PAHs) belong to a large group of organic pollutant which considers as a potential health hazard to living beings. Herein, naphthalene biodegradation potential by free and immobilizedPseudomonas putidastrain KD10 andPseudomonassp. consortium were studied. Additionally, naphthalene 1, 2-dioxygenase (nahAc) was sequenced and analyzed, which reveals two altered amino acid residues. However, the altered amino acid residues are not present in the vicinity of the active site. The gas-phase binding free energy (ΔGLondon) of the mutant variant of naphthalene 1, 2-dioxygenase was -7.10 kcal mol-1which closely resembles the wild type variant. Naphthalene biodegradation rate byPseudomonas putidastrain KD10 was 79.12 mg L-1day-1and it was significantly elevated up to 123 mg L-1day-1by the immobilizedPseudomonassp. consortium. The half-life (t1/2) for naphthalene biodegradation was 3.1 days with the inhibition constant (ki), substrate saturation constant (ks) and maximum specific degradation rate constant (qmax) of 1268 mg L-1, 395.5 mg L-1and 0.65 h-1, respectively, for thePseudomonas putidastrain KD10. However, the t1/2value was significantly reduced to 2 days along withki,ksandqmaxvalues of 1475 mg L-1, 298.8 mg L-1and 0.71 h-1, respectively, by the immobilizedPseudomonassp. consortium. The GC-MS data suggest that KD10 might follow D-gluconic acid mediated meta-cleavage pathway of catechol biodegradation. It is concluded that naphthalene biodegradation performance by immobilizedPseudomonassp. consortium was superior to free or immobilizedPseudomonas putidaKD10. Microbial consortium immobilization could be a useful tool for water quality management and environmental remediation.HighlightsSuperior naphthalene biodegradation byPseudomonassp. consortium immobilized in calcium alginate beads.A common mutation prone amino acid stretch inside chain A of naphthalene 1, 2-dioxygenase has been identified.A new naphthalene biodegradation pathway byPseudomonas putidastrain KD10 has been proposed. |
