chemoautotrophs
Chemoautotrophs are cells that break down inorganic molecules to supply energy for the cell, and use carbon dioxide as a carbon source. Chemoautotrophs include prokaryotes that break down hydrogen sulfide H 2 S the rotten egg smelling gas , and ammonia NH 4 . Nitrosomonas , a species of soil bacterium, oxidizes NH 4 + to nitrite NO 2 - . This reaction releases energy that the bacteria use. Many chemoautotrophs also live in extreme environments such as deep sea vents.