Microbial remediation of PAHs in aquatic environments: advances, ssynergistic mechanisms, and emerging strategies.

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants widely distributed in aquatic environments, originating from fossil fuel combustion, oil spills, industrial emissions, and increasingly, wildfires. While microbial degradation represents a green and effective remediation strategy, single microorganisms exhibit limited metabolic capacity. This review demonstrates that synergistic multi-kingdom consortia involving bacteria, fungi, and microalgae achieve substantially higher degradation efficiencies (up to 100% for phenanthrene and pyrene in optimized co-cultures) through three core mechanisms: (i) extracellular polymeric substance (EPS)-mediated pollutant enrichment, which increases local PAH concentration by 5.0-4.5% for pyrene and benzo[a]pyrene; (ii) oxidative stress regulation via coordinated enzymatic and non-enzymatic antioxidant systems; and (iii) interspecies metabolic exchange, including photosynthetic oxygen supply from microalgae to bacterial and fungal pre-oxidation of HMW PAHs into bacterial-mineralizable intermediates. Bibliometric analysis of 1,508 publications (2020-2026) reveals a paradigm shift from single-strain screening toward mechanistic elucidation of interspecies interactions, with "metabolites," "mechanisms," and "bacterial diversity" emerging as burst keywords. Emerging enhancement strategies, including biosurfactant supplementation, microbial immobilization on biochar carriers, and genetic engineering of ring-hydroxylating dioxygenases-are critically evaluated. However, field application remains challenged by environmental matrix complexity, competition with indigenous microbiota, and emerging anthropogenic stressors such as microplastics that alter microbial community assembly. This review provides an integrated mechanistic and strategic framework for developing efficient, resilient, and sustainable PAH bioremediation technologies in aquatic systems.