which are the microorganisms that are useful in nitrogen cycle ?
1. Bacteria that nitrifies ammonium compounds in the (called ""). Example: Nitrosomonas.
2. Bacteria that nitrifies nitrites (NO2-) in the soil (also called "nitrifying bacteria"). Example: Nitrobacter.
3. Bacteria that denitrifies nitrates (NO3-) in the soil (called ""). Example: Pseudomonas denitrificans.
4. Bacteria that "fixes" nitrogen (called "nitrogen-fixing bacteria"). Examples: Rhizobium (which is symbiotic) and Azotobacter (which is free-living).
5. You also have bacteria that putrefies nitrogenous waste (like urea) and the protein in dead organisms. This type of bacteria is called putrefying bacteria.