Share on Facebook Share on Twitter Email
Answers.com

Aerobic organism

 
Sci-Tech Dictionary: obligate aerobe
(¦äb·lə′gāt ′er·ōb)

(microbiology) A microorganism that uses oxygen for cellular respiration and requires some free molecular oxygen in its surroundings to support growth.


Search unanswered questions...
Enter a question here...
Search: All sources Community Q&A Reference topics
Medical Dictionary: obligate aerobe
Top

n.

An organism, such as a bacterium, that can live only in the presence of oxygen.

Wikipedia: Aerobic organism
Top
Aerobic and anaerobic bacteria can be identified by growing them in a liquid culture:
1: Obligate aerobic 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.

An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment. [1]

Contents

Types

Glucose

A good example would be the oxidation of glucose (a monosaccharide) in aerobic respiration.

C6H12O6 + 6 O2 + 38 ADP + 38 phosphate → 6 CO2 + 6 H2O + 38 ATP

Notice that oxygen is used during the oxidation of glucose and water is produced.

This equation is a summary of what actually happens in three series of biochemical reactions: glycolysis, the Krebs cycle, and oxidative phosphorylation.

Diversity

Almost all animals, most fungi, and several bacteria are obligate aerobes. Most anaerobic organisms are bacteria. Being an obligate aerobe - although advantageous from the energetical point of view, also means obligatory exposure to high levels of oxidative stress.

Yeast is an example of a facultative aerobe. Individual human cells are also facultative aerobes: they switch to lactic acid fermentation if oxygen is not available. However, for the whole organism this cannot be sustained for long, and humans are therefore obligate aerobes.

References

See also


 
 

 

Copyrights:

Sci-Tech Dictionary. McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved.  Read more
Medical Dictionary. The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Aerobic organism" Read more