Anaerobic ammonia oxidizing (Anammox) bacteria play a crucial role in the global microbial nitrogen cycle It has been estimated that 50% of the removal of reactive nitrogen as N2 gas in the sea occurs through the anammox process Their discovery in the early 90s gave birth to a new research field that revolutionized our understanding of the microbial nitrogen cycle and enabled the development of novel and more efficient wastewater treatment technologies Until now these bacteria have only been cultured under mesophilic conditions and their biotechnological application is limited to wastewater at temperatures below 40°C At Ghent University we have been able to cultivate a new species of anammox bacteria that grows under thermophilic conditions In this project we aim at understanding its metabolism, the capabilities of thermophilic anammox bacteria and their ecological role in natural and engineered systems This project will enable revisiting the microbial nitrogen cycle, improve our understanding of the mysteries of the thermophilic nitrogen microbiology and provide the first clues for the application of anammox bacteria to the thermophilic treatment of nitrogen polluted wastewaters