Missing lithotroph identified as new planctomycete

With the increased use of chemical fertilizers in agriculture, many densely populated countries face environmental problems associated with high ammon ia emissions. The process of anaerobic ammonia oxidation ('anammox') is one of the most innovative technological advances in the removal of ammonia ni trogen from waste water(1,2). This new process combines ammonia and nitrite directly into dinitrogen gas(3). Until now, bacteria capable of anaerobica lly oxidizing ammonia had never been found and were known as "lithotrophs m issing from nature"(4). Here we report the discovery of this missing lithot roph and its identification as a new, autotrophic member of the order Planc tomycetales, one of the major distinct divisions of the Bacteria(5). The ne w planctomycete grows extremely slowly, dividing only once every two weeks. At present, it cannot be cultivated by conventional microbiological techni ques. The identification of this bacterium as the one responsible for anaer obic oxidation of ammonia makes an important contribution to the problem of unculturability.