Biodegradation of Phenanthrene by Alcaligenes ammonioxydans, (VITRPS2) strain isolated from petroleum contaminated soil: Degradation, Inhibition kinetics and metabolic pathway

Abstract

The compound, Phenanthrene, a three-ring polyaromatic hydrocarbon (PAH) commonly occurs in the environment and it is derived from grilled meals, tobacco, crude oil, coal tar and automobile exhaust among other sources. Phenanthrene has been identified as a potentially hazardous PAH. Bioremediation is the most popular way of elimination technique since it is a sustainable solution that results in full mineralization of Phenanthrene. In this study, we aim to perform the biodegradation of phenanthrene by using the strain, Alcaligenes ammonioxydans (VITRPS2) which is isolated from petroleum-contaminated soil. At 5 mg/ml, the degradation rate constant was found to be 0.0181/day with half-life values of 2.7 as per first-order kinetics and 4.49 as per second-order kinetics. We employed one factor at a time (OFAT) approach to optimize the biodegradation conditions of the strain within the framework of Luria‐Bertani (LB) media. The isolate exhibited the ability to achieve maximum growth of 5mg/ml of phenanthrene as the exclusive carbon source under optimal conditions. These conditions included a pH level of 8.0, an inoculum concentration of 8%, along with a temperature of 37°C throughout 7 days of incubation period. The strain exhibited a degradation efficiency of up to 72% for phenanthrene, given optimal environmental conditions. The gas chromatography-mass spectrometry (GC-MS) analysis of the breakdown products unveiled the existence of the principal metabolites of the pathway, such as salicylic acid, catechol & various phthalic acid derivatives. The strain demonstrates that there are considerable potential applications in the remediation of an environment polluted by polycyclic aromatic hydrocarbon (PAH) metabolites.