Exploring the Mysteries of Nitrogen-Transforming Microorganisms: Investigating the Potential Role of Aerobic Denitrification in Nitrogen Cycling in Reservoir Water Sources

Nitrogen management is essential for fostering environmental sustainability in source water reservoirs. A comprehensive analysis conducted in both southern and northern China revealed significant spatial and temporal variations in total nitrogen concentrations, particularly elevated during the thermal stratification period. Notably, Acinetobacter emerged as prevalent aerobic denitrifying bacteria, while Ralstonia, Permianibacter, Aeromonas, and Bradyrhizobium had multiple contributions to nitrogen metabolism beyond aerobic denitrification. The emergence of anaerobic zones limited the abundance of aerobic denitrifying bacteria. As the activity of these bacteria increased, nitrate concentrations decreased, demonstrating biological control of the denitrification process. During thermal stratification, an increase in the abundance of key genes (napAB, nirK, norBC) was associated with lower nitrogen concentrations, highlighting the critical role of the nap-type gene in facilitating aerobic denitrification in reservoirs. This study provides novel insights into the mechanisms by which microorganisms regulate water quality and mitigate nitrogen pollution, emphasizing the intricate relationship between microbial dynamics and environmental health in aquatic ecosystems.