Harnessing native microbes: Intermittent aeration for bioremediation of phenolic compounds contaminated freshwater

Phenolic pollutants pose persistent risks to freshwater ecosystems due to their toxicity, structural diversity, and resistance to biodegradation. This study investigated microbial community dynamics, gene-level adaptation, and biostimulation strategies for phenolic removal using native microbial community. Metagenome analyses revealed marked taxonomic shifts under phenolic stress, with engineered systems favoring modular cooperative degradation, whereas the natural community relied on dominance of stress-resistant taxa and inter-phylum horizontal gene transfer (HGT). Functional profiling identified 28 candidate KEGG Orthologs (KOs), including oxidative, ring-cleaving, and energy-support genes, enriched across core degraders such as Pseudomonas, Sphingobium, and Bordetella. Biostimulation assays demonstrated oxygen availability as the primary limiting factor: intermittent aeration (IA) enhanced phenolic degradation by 29%, while IA combined with activated carbon (IA + AC) achieved up to 75% improvement, especially for complex compounds like bisphenol A (BPA) and nitrophenol. Predictive modeling based on KO abundance and stimulation methods (R² = 0.75-0.88) successfully predicted degradation performance across 50 natural samples. While IA + AC provided the most consistent improvement, 15 communities achieved comparable efficiencies under IA alone, highlighting context-dependent biodegradation capacities linked to HGT and metabolic pathway diversity. These findings establish a scalable predictive framework and emphasize the importance of tailoring biostimulation strategies to native microbial capacities, offering a practical route for in situ bioremediation of phenol-contaminated freshwater systems.