Enhanced biodegradation of naphthalene by Pseudomonas sp. consortium immobilized in calcium alginate beads

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 immobilized strain KD10 and sp. consortium were studied. Additionally, naphthalene 1, 2-dioxygenase (Ac) 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 (ΔG) of the mutant variant of naphthalene 1, 2-dioxygenase was -7.10 kcal mol which closely resembles the wild type variant. Naphthalene biodegradation rate by strain KD10 was 79.12 mg L day and it was significantly elevated up to 123 mg L day by the immobilized sp. consortium. The half-life () for naphthalene biodegradation was 3.1 days with the inhibition constant (), substrate saturation constant () and maximum specific degradation rate constant () of 1268 mg L, 395.5 mg L and 0.65 h, respectively, for the strain KD10. However, the t value was significantly reduced to 2 days along with , and values of 1475 mg L, 298.8 mg L and 0.71 h, respectively, by the immobilized sp. 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 immobilized sp. consortium was superior to free or immobilized KD10. Microbial consortium immobilization could be a useful tool for water quality management and environmental remediation.