Plant Microbe Synergistic Rhizoremediation Mechanisms for Polycyclic Aromatic Hydrocarbon Contaminated Soils in the Nigerian Environmen

Abstract

Polycyclic aromatic hydrocarbons (PAHs) constitute a formidable class of persistent organic pollutants with significant implications for environmental quality, ecosystem stability, and public health globally. In Nigeria, a nation characterized by extensive petroleum industry activities, rapid urbanization, and agricultural expansion, PAH contamination presents a critical and multifaceted environmental challenge. Conventional physicochemical remediation technologies are frequently constrained by high economic costs, substantial energy requirements, and the potential for secondary environmental disruption. Consequently, biological remediation strategies, particularly those leveraging the synergistic interactions between plants and microorganisms (rhizoremediation), have emerged as a scientifically robust, ecologically sustainable, and potentially cost-effective alternative. This comprehensive review article meticulously examines the intricate molecular, biochemical, and ecological mechanisms that underpin the synergistic degradation of PAHs by plant-microbe partnerships. We provide a detailed analysis of microbial catabolic pathways, including the pivotal role of dioxygenase enzyme systems in aerobic bacteria and the non-specific oxidative mechanisms employed by ligninolytic fungi. The review elucidates the active role of plants in facilitating remediation through rhizosphere engineering, focusing on the critical function of root exudates as biochemical signals and bioavailability enhancers. A dedicated and substantial section of this work contextualizes these mechanisms within the Nigerian environment, analyzing prevalent contamination sources, screening indigenous biological resources with demonstrated or potential bioremediation capabilities, and discussing the unique pedoclimatic and socio-economic factors that influence implementation. We further explore advanced enhancement strategies such as tailored bioaugmentation, targeted biostimulation, and the integration of novel materials, alongside the transformative potential of omics technologies for understanding and optimizing these complex biological systems. Finally, the article proposes a forward-looking framework for translating this green technology from controlled research settings to effective field-scale application within Nigeria, emphasizing its integration into a broader sustainable bioeconomy and land management strategy to address the nation's specific pollution legacy.