Enhanced Aerobic Naphthalene Degradation Utilizing Indigenous Microbial Flora as a Biocatalyst in Oil-Contaminated Wastewater

Abstract

Bacteria indigenous to oil-contaminated water exhibited diverse metabolic capabilities in degrading various aromatic and monoaromatic hydrocarbons. Out of the 28 bacterial strains isolated from the wastewater, each was cultivated with at least one hydrocarbon, including kerosene, naphthalene, toluene, diesel, or aniline. Among these strains, Pseudomonas putida AD-128 emerged as one of the most effective polyaromatic hydrocarbon (PAH) degraders. Following a 6-day treatment period, strain P. putida AD-128 demonstrated proficiency in degrading various PAHs, including naphthalene, phenanthrene, and fluorine. After 6 days of incubation at 20 °C, the degradation of Naphthalene (NAP) notably increased. Gas Chromatography Mass Spectrometry analysis identified the degraded compounds, including pyruvic acid, salicylaldehyde, D-gluconic acid, and catechol. Optimal NAP degradation was observed at 20 °C and pH 6.0, with increased agitation speed correlating with enhanced bacterial growth and heightened degradation, particularly evident after 6 days at 20 °C. Peptone emerged as the most effective among the four nitrogen supplements (ammonium sulfate, potassium nitrate, beef extract, and peptone), significantly reducing residual naphthalene in the medium. The isolated indigenous bacterium, P. putida AD-128, exhibits robust capabilities in degrading PAHs under optimized conditions, making it a valuable asset for environmental management initiatives.