1: Obligate aerobic (oxygen-needing) bacteria gather at the top of the test tube in order to absorb maximal amount of oxygen.
2: Obligate anaerobic bacteria gather at the bottom to avoid oxygen.
3: Facultative bacteria gather mostly at the top, since aerobic respiration is the most beneficial one; but as lack of oxygen does not hurt them, they can be found all along the test tube.
4: Microaerophiles gather at the upper part of the test tube but not at the top. They require oxygen but at a low concentration.
5: Aerotolerant bacteria are not affected at all by oxygen, and they are evenly spread along the test tube.
Microaerophilic organisms are a specific type of microorganism (especially bacteria) that requires oxygen to survive, but requires environments containing lower levels of oxygen than are present in the atmosphere (~20% concentration). Many microphiles are also capnophiles, as they require an elevated concentration of carbon dioxide. (In the laboratory they can be easily cultivated in a candle jar, a container into which a lit candle is introduced before sealing the airtight lid. The flame burns until extinguished by oxygen deprivation, creating a carbon dioxide-rich, oxygen-poor atmosphere.)
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Examples
Examples include:
- Borrelia burgdorferi, a species of spirochaete bacteria that causes Lyme disease in humans.
- Helicobacter pylori, a species of proteobacteria that has been linked to peptic ulcers and some types of gastritis. Some don't consider it a true obligate microaerophile.[1]
- Campylobacter has been described as microaerophilic.[2]
- Streptococcus intermedius has also been described as microaerophilic.
See also
- Aerotolerant organism
- Aerobic organism
- Anaerobic organism
- Facultative anaerobic organism
- Fermentation (biochemistry)
References
- ^ Bury-Moné S, Kaakoush NO, Asencio C, et al. (August 2006). "Is Helicobacter pylori a true microaerophile?". Helicobacter 11 (4): 296–303. doi:. PMID 16882333. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=1083-4389&date=2006&volume=11&issue=4&spage=296.
- ^ Fernie DS, Park RW (August 1977). "The isolation and nature of campylobacters (microaerophilic vibrios) from laboratory and wild rodents". J. Med. Microbiol. 10 (3): 325–9. PMID 330861.
External links
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