Exploring patterns and mechanisms of indigenous microbial community succession driven by polycyclic aromatics in heterotrophic nitrification and aerobic denitrification systems

Although heterotrophic nitrification and aerobic denitrification process can efficiently remediate polycyclic aromatic hydrocarbons (PHAs) contamination in aquatic environments, the succession patterns and potential mechanisms of PAHs-driven microbial communities remain unclear. This study established the microcosms containing phenanthrene (PHE) pollution to address the aforementioned issues. Key genes and enzymes revealed that PHE impacted nitrogen conversion efficiency by inhibiting carbon and nitrogen metabolism, while ammonia nitrogen assimilation and nitrate nitrogen dissimilatory reduction were the main nitrogen transformation pathways. Meanwhile, PHE enhanced species specialization during community succession, allowing specialized species with environmental functions to reorganize microbial communities. These functional microbes resisted and degraded PHE pollutants through strengthened quorum sensing, ABC transporters and carbon metabolism. In addition, microbial community succession was jointly controlled by the synergistic effects between microbes and the heterogeneous selection patterns induced by PHE. This study provides valuable reference and theoretical basis for the bioremediation of PAHs-contaminated water bodies.