Ammonia nitrogen degradation metabolic pathway by the novel strain Paracoccus sp. TD-10 and its molecular mechanisms

Heterotrophic nitrification-aerobic denitrification（HN-AD） bacteria have attracted significant attention due to their high tolerance for ammonia nitrogen, efficient ammonia nitrogen degradation capabilities, and strong environmental adaptability in removing nitrogen contaminants from residential and industrial wastewater. This study aimed to investigate the ammonia nitrogen degradation characteristics of a novel HN-AD strain with superior ammonia nitrogen degradation capacity, providing a foundation for optimizing the ammonia nitrogen degradation processes in wastewater treatment facilities. The ammonia nitrogen degradation ability of Paracoccus sp. TD-10 was evaluated under specific conditions: pH 9.0, 28 ℃ and an initial concentration of 100.0 mg/L NH₄⁺, with sodium acetate serving as both the carbon and energy source. The results demonstrated a 100 % degradation rate under these conditions. Whole-genome analysis, functional gene identification, and nitrogen balance studies suggested a potential ammonia degradation pathway: NO₃⁻-N → NO₂⁻-N → NO → N₂O → N₂, and NH₄⁺-N → Gln → Glu. The exceptional ammonia nitrogen degradation efficiency of strain TD-10, combined with its ability to prevent the accumulation of nitrite and nitrate nitrogen, offers a solid theoretical basis for optimizing HN-AD bacteria in the sewage ammonia nitrogen degradation process.