Enhanced biodegradation of naphthalene byPseudomonassp. consortium immobilized in calcium alginate beads

Abstract

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 Pseudomonas putida strain KD10 and Pseudomonas sp. 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-1 which closely resembles the wild type variant. Naphthalene biodegradation rate by Pseudomonas putida strain KD10 was 79.12 mg L-1 day-1 and it was significantly elevated up to 123 mg L-1 day-1 by the immobilized Pseudomonas sp. 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-1 and 0.65 h-1, respectively, for the Pseudomonas putida strain KD10. However, the t1/2 value was significantly reduced to 2 days along with ki, ks and qmaxvalues of 1475 mg L-1, 298.8 mg L-1 and 0.71 h-1, respectively, by the immobilized Pseudomonas 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 Pseudomonas sp. consortium was superior to free or immobilized Pseudomonas putida KD10. Microbial consortium immobilization could be a useful tool for water quality management and environmental remediation.HighlightsSuperior naphthalene biodegradation by Pseudomonas sp. 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 by Pseudomonas putida strain KD10 has been proposed.

Bacterial chemotaxis: a way forward to aromatic compounds biodegradation

“…Commonly PAHs degradation is initiated by ring hydroxylating dioxygenase [136]. Naphthalene degradation in Pseudomonas putida KD10 follows the metacleavage pathway of catechol [137]. Stenotrophomonas maltophilia C6 possesses multiple degradation pathways for phenanthrene [138].…”

Microbial characterization of a facultative residual sludge obtained from a biogas plant with ability to degrade commercial B10 diesel oil

“…This enhancement could be achieved by several ways such as, different biodegradation pathways of each individual bacterium, metabolic intermediates of one bacterium that may act as the starting material of another, different genetic makeup, or by synthesising different variants of the same catalytic enzymes (Obayori et al, 2009;Kumari et al, 2018). Re cently, Dutta et al (2019) have reported that a microbial consortium of Pseudomonas sp. may be superior to the free Pseudomonas strains in polycyclic aromatic hydrocarbon biodegradation since the epigenetic impacts on the metabolic enzymes.…”