Nitrospina, and Nitrococcus are also known to convert nitrite into nitrate.
They are mesophiles, with a temperature optimum of 28oC and a pH range of 5.8-8.5, with an optimum pH range between 7.6 and 7.8.
The nitrates that are formed may now serve as fertilizer for most plants. It requires about 4.5 parts of oxygen to convert one (1) part of "ammonia nitrogen" into "nitrate nitrogen".
For a "basic summary" then, nitrification means the conversion of ammonia into nitrites; then the nitrites into nitrates.