Energy Release by Prokaryotes
| Mode of Metabolism | How Energy is Released | Habitat | Example |
|---|
| Obligate aerobe “requiring oxygen” | Cellular respiration; must have ready supply of Oxygen to release fuel energy | Oxygen-rich environments, such as near water surface or in animal lungs | Mycobacterium tuberculosis: Sometimes found in human lungs |
| Obligate anaerobe “requiring a lack of oxygen” | Fermentation; die in presence of oxygen | Environments lacking Oxygen such as deep soil, animal intestines, or airtight containers | Clostridium botulinum: Sometimes found in improperly sterilized canned food, causing food poisoning |
| Facultative anaerobe “surviving without oxygen when necessary” | Can use either cellular respiration or fermentation as necessary | Oxygen-rich or oxygen-poor environments | E. coli: Lives aerobically in sewage and anaerobically in human large intestine |