Microbial roles in the terrestrial and aquatic nitrogen cycle-implications in climate change

Nitrogen, as an essential component for living organisms, is the primary limiting nutrient on Earth. The availability and effective utilization of nitrogenous compounds for metabolic and other essential biochemical reactions are dependent on the myriad and phylogenetically diverse microbial communities. The microorganisms harmoniously interact and participate in every reaction of the nitrogen cycle to continuously transform nitrogen into its various bio-available forms. Research on the nitrogen cycle continues to disclose that there are many reactions that remain unknown. In this review, we summarize the recent discoveries that have contributed to advancing our understanding of the microbial involvement in reactions of the nitrogen cycle in soil and aquatic systems that influence climate change. Additionally, the mini-review highlights, which anthropogenic activities cause disturbances in the nitrogen cycle and proposes how beneficial microbes may be harnessed to replenish nitrogen in agricultural ecosystems.