Editing Commensalism (section)

=== ''Nitrosomonas'' spp and ''Nitrobacter'' spp ===
Commensalistic relationships between microorganisms include situations in which the waste product of one microorganism is a substrate for another species. One good example is nitrification — the oxidation of [[ammonium|ammonium ion]] to [[nitrate]]. Nitrification occurs in two steps: first, bacteria such as ''[[Nitrosomonas]]'' [[Species#Abbreviations|spp.]] and certain [[crenarchaeota|crenarchaeote]]s oxidize ammonium to [[nitrite]]; and second, nitrite is oxidized to nitrate by ''[[Nitrobacter]]'' spp. and similar bacteria. ''Nitrobacter'' spp. benefit from their association with ''Nitrosomonas'' spp. because they use nitrite to obtain energy for growth.{{cn|date=June 2024}}

Commensalistic associations also occur when one microbial group modifies the environment to make it better suited for another organism. The synthesis of acidic waste products during [[fermentation]] stimulates the proliferation of more acid-tolerant microorganisms, which may be only a minor part of the microbial community at neutral pH. A good example is the succession of microorganisms during milk spoilage.{{cn|date=June 2024}}

[[Biofilm]] formation provides another example. The colonization of a newly exposed surface by one type of microorganism (an initial colonizer) makes it possible for other microorganisms to attach to the microbially modified surface.{{cn|date=June 2024}}