sentence: Cyanobacteria are in most environments on Earth.
sentences_after: They play key roles in the carbon and nitrogen cycle of the biosphere. Cyanobacteria use many sources of combined nitrogen, like nitrate, nitrite, ammonium, urea, or some amino acids.
concept_name: Cyanobacteria
headings: Nitrogen fixation Biological Microorganisms that fix nitrogen (diazotrophs) Nitrogen fixation by cyanobacteria
categories: Ecology Biochemistry