Microaerophile

Aerobic and anaerobic bacteria can be identified by growing them in liquid culture:
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.

A microaerophile is a microorganism 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 candle jar is a container into which a lit candle is introduced before sealing the container's airtight lid. The candle's flame burns until extinguished by oxygen deprivation, which creates a carbon dioxide-rich, oxygen-poor atmosphere in the jar.

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.
• Streptococcus pyogenes, a well known microaerophile that causes streptococcal pharyngitis.

See also

• Aerotolerant organism
• Aerobic organism
• Anaerobic organism
• Facultative anaerobic organism
• Fermentation (biochemistry)

References

1. ^ Bury-Moné S, Kaakoush NO, Asencio C, et al. (August 2006). "Is Helicobacter pylori a true microaerophile?". Helicobacter 11 (4): 296–303. doi:10.1111/j.1523-5378.2006.00413.x. 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. 
2. ^ 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. doi:10.1099/00222615-10-3-325. PMID 330861. 

External links

• Characterization of an unclassified microaerophilic bacterium associated with gastroenteritis.