Indigenous Fungal Consortium and Solanum lycopersicum Synergistically Remediate Aged PAH-Contaminated Soils and Restore Soil Functionality in the Niger Delta

Polycyclic aromatic hydrocarbons (PAHs) are among the most persistent and hazardous contaminants in petroleum-polluted soils, particularly in chronically impacted regions where ageing processes reduce contaminant bioavailability and hinder remediation. This study evaluated the effectiveness of an indigenous fungal consortium, alone and in combination with Solanum lycopersicum L., for the remediation of aged PAH-contaminated soils collected from four historically polluted sites in the Niger Delta, Nigeria. A consortium comprising ten hydrocarbon-tolerant fungal strains belonging to the genera Aspergillus, Meyerozyma, Moniliella, Paecilomyces, Penicillium, and Trichoderma was applied in a 90-day microcosm experiment under four treatments: untreated soil (BS), plant only (BSP), fungal consortium only (BSF), and fungal consortium plus plant (BSPF). Remediation performance was assessed through the quantification of 16 priority PAHs and changes in key soil physicochemical properties.,The combined fungi-plant treatment (BSPF) consistently achieved the greatest remediation efficiency across all sites. Total low-molecular-weight PAHs were reduced by 72-83%, while high-molecular-weight PAHs declined by 65-75% relative to initial concentrations. Significant reductions were also observed for carcinogenic PAHs, with concentrations decreasing by up to 74.8% in the most heavily contaminated soil. In addition to contaminant removal, BSPF substantially improved soil quality indicators. Soil pH increased from highly acidic conditions (3.8-4.3) to near-neutral values (6.1-7.6), available phosphorus increased by up to 78%, and organic carbon content increased across treated soils. The fungal consortium alone also enhanced PAH degradation and soil recovery compared with untreated controls; however, its performance was consistently lower than that of the integrated fungi-plant system.,The results demonstrate that synergistic interactions between indigenous hydrocarbon-degrading fungi and S. lycopersicum can simultaneously accelerate PAH dissipation and restore soil functionality in aged petroleum-contaminated soils. This low-input, biologically based strategy offers a promising and sustainable remediation approach for long-term hydrocarbon-impacted environments in tropical regions.