Abstract
Nitrifying bacteria are specialized microorganisms that actively participate in the nitrification process, which involves the conversion of ammonia (NH3) into nitrite (NO2-) and subsequently into nitrate (NO3-). Extensive human activities such as agriculture, thermal power generation, and automobile exhaust have led to an increase in the amounts of greenhouse gases and nitrogen pollution in soil and water. This comprehensive review highlights the importance of nitrogen-related processes for environmental sustainability and the role of nitrifying bacteria in combating nitrogen pollution. The focus of the current work is a detailed exploration of the diverse classes of nitrifying bacteria and their respective roles in environmental processes. Furthermore, the study explores practical applications of different classes of nitrifying bacteria, extending beyond the nitrification process. This review explored the potential of nitrifying bacteria in wastewater treatment, biodegradation of micropollutants, and the treatment of municipal solid waste leachate, showcasing the versatility of these bacteria in addressing broader environmental challenges.