Optimization of Physicochemical Conditions for the Phenanthrene Degrading Consortium NS-PAH-2015-PNP-5

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are widespread ecological contaminants. These are produced as a result of diverse natural and anthropogenic activities. Phenanthrene is a low molecular weight PAH and is found prominently around the petrochemical contaminated sites. The increasing environmental concentration of phenanthrene is a threat to the ecosystems and their natural functioning. The present study developed a phenanthrene degrading bacterial consortium NS-PAH-2015-PNP-5 from the petrochemical contaminated soil near the Indian Oil Corporation Limited (IOCL) refinery, Panipat (India). The sample soil's pH, EC, TOC, and phenanthrene concentrations were 7.9, 1.81dS/m, 4.2%, and 19.7 mg/kg, respectively. Results from the 16S rRNA metagenome analysis of the consortium NS-PAH-2015-PNP-5 have shown an overwhelming population of Proteobacteria and Pseudomonas spp. at the respective phylum and species diversity. Response surface methodology (RSM) of statistical optimization tool ‘Design-Expert’ was used to optimize the physicochemical conditions for the phenanthrene biodegradation study. In the experiment, three factors, including temperature, pH, and concentration of phenanthrene, were optimized against the single response phenanthrene degrading efficiency (%). The gas chromatographic analysis results showed that a phenanthrene degrading efficiency of 89% was obtained at optimized physicochemical conditions (i.e., 35 °C temperature, pH 7.3, and 869 ppm concentration of phenanthrene) after 7 days of incubation of NS-PAH-2015-PNP-5 at a constant shaking rate of 100 rpm. Highlights: Bacterial consortium NS-PAH-2015-PNP-5 having a foremost population of phylum Proteobacteria, was developed from the petrochemical contaminated soil. A synergistically improved rate of phenanthrene biodegradation by NS-PAH-2015-PNP-5 was achieved at optimized physicochemical conditions using the Design-expert.