Abstract: Anaerobic ammonium oxidation (anammox) is an important discovery in microbiology and environmental sciences, which can simultaneously remove NH4+-N and NO3--N, being valuable in environmental engineering. However, anaerobic ammonium oxidizers are extremely slow-growing, and their population’s doubling time is longer than 11 days, which seriously restricts the application of anammox process. Therefore, the study of anammox bacteria is of significance. It has been proved that besides planctomycetes, the first recognized anammox bacteria, both nitrifying bacteria and denitrifying bacteria are also capable of anaerobic ammonium oxidation. These anammox bacteria have wide-spread habitats, which offered a chance to exploit new bacterial resources for anammox. Nitrifying bacteria and denitrifying bacteria have the function of anammox, and their metabolic diversity provides a basis to speed up the start-up of anammox reactor. It was revealed that anaerobic digestion sludge can present anammox activity, with sulphate as electron acceptor. The new bioreaction lays a foundation for the development of novel N-removal biotechnology, being conducive to the development and application of anammox to get more bacterial resources for anammox and to make clear the ecological distribution of anammox bacteria.

Key words: natural larch forest, wood-decaying fungi, species diversity.