Degradation and inhibition kinetics of phenanthrene by Alcaligenes ammonioxydans, [VITRPS2] strain isolated from petroleum-contaminated soil

Abstract

Phenanthrene, a common three-ring polyaromatic hydrocarbon [PAH], originates from sources like grilled meals, tobacco, crude oil, coal tar, and automobile exhaust. Recognized as a hazardous PAH, it is often targeted for bioremediation due to its sustainability and potential for full mineralization. In this study, we focus on biodegrading phenanthrene using the strain Alcaligenes ammonioxydans [VITRPS2], isolated from petroleum-contaminated soil. At 5 mg/ml, degradation occurred at a rate constant of 0.0181/day, with half-life values of 2.7 and 4.49 according to first and second-order kinetics, respectively. Employing a one-factor-at-a-time [OFAT] approach, we optimized biodegradation conditions within Luria–Bertani [LB] media. Under optimal conditions—pH 8.0, 8% inoculum concentration, and 37 °C incubation over seven days—the strain achieved maximal growth with phenanthrene as the sole carbon source. It exhibited a degradation efficiency of up to 72% for phenanthrene under these conditions. Gas chromatography-mass spectrometry [GC–MS] analysis revealed principal metabolites of the breakdown pathway, including salicylic acid, catechol, and various phthalic acid derivatives. This underscores the strain's potential for remediating environments polluted by PAH metabolites, showcasing its remarkable capability for complete phenanthrene degradation.Graphical abstract