Research progress and application prospects of heterotrophic nitrification-aerobic denitrification bacteria in marine environments

The problem of marine nitrogen pollution is becoming increasingly severe, necessitating the development of efficient and sustainable denitrification microbial technologies. Heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria have garnered significant attention in recent years due to their ability to efficiently convert ammonia nitrogen to gaseous nitrogen under aerobic conditions, making them a focus of research on marine water quality remediation. This review systematically examines the main classifications and ecological characteristics of marine HN-AD bacteria, analyzing their adaptability and nitrogen metabolism characteristics in typical marine environments with high salinity, high ammonia, and low C/N ratios. It also summarizes current methods for screening and isolating strains, with a particular focus on the impact mechanisms of key environmental factors such as carbon sources, salinity, heavy metals, DO, and carbon source concentrations on denitrification efficiency. This review aims to provide a theoretical foundation and research directions for the subsequent development of functional strains, process regulation mechanisms, and marine ecological remediation practices, thereby promoting the scientific transformation and wide application of HN-AD bacteria in marine environmental management.