Biodegradation of naphthalene, phenanthrene, and pyrene by four indigenous fungal species isolated from petrochemical refinery effluent

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants of global environmental concern due to their toxicity and resistance to degradation. Traditional remediation approaches are often costly and unsustainable. This study investigated the potential
of four fungal species isolated from petrochemical refinery effluent in the biodegradation of selected PAHs (naphthalene, phenanthrene, and pyrene). Molecular identification of fungi was conducted by PCR amplification and sequencing of the internal transcribed spacer (ITS) region. The fungal isolates were evaluated for PAH degradation capabilities at concentrations of 100, 150, and 200 mg/L. The residual PAHs were analysed using UV spectroscopy analysis and the percentage of each PAH removal was calculated. The four fungi were identified as Talaromyces purpureogenus, Trichoderma harzianum, Aspergillus flavus, and Fusarium oxysporum. Trichoderma harzianum
showed the highest degradation efficiency across all concentrations, followed by Fusarium oxysporum, Aspergillus flavus, and Talaromyces purpureogenus. Degradation ranges were 92.6 ± 0.12% – 99.6 ± 0.06%, for naphthalene, 78.3 ± 0.12% – 99.1 ± 0.06% for phenanthrene, and 39.1 ± 0.06% – 95.3% ± 0.15% for pyrene. The results demonstrate that these fungi, especially Trichoderma harzianum and Fusarium oxysporum are potentially valuable species for environmentally friendly bioremediation of PAH-contaminated sites. This study underscores the potential application of indigenous fungal species in sustainable remediation of PAHcontaminated environments particularly in developing countries like Nigeria and supports their inclusion in future environmental clean-up strategies.