Aerobic organism

An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment.[1] In contrast, an anaerobic organism (anaerobe) is any organism that does not require oxygen for growth. Some anaerobes react negatively or even die if oxygen is present.[2]

Aerobic and anaerobic bacteria can be identified by growing them in test tubes of thioglycollate broth:
1: Obligate aerobes need oxygen because they cannot ferment or respire anaerobically. They gather at the top of the tube where the oxygen concentration is highest.
2: Obligate anaerobes are poisoned by oxygen, so they gather at the bottom of the tube where the oxygen concentration is lowest.
3: Facultative anaerobes can grow with or without oxygen because they can metabolise energy aerobically or anaerobically. They gather mostly at the top because aerobic respiration generates more ATP than either fermentation or anaerobic respiration.
4: Microaerophiles need oxygen because they cannot ferment or respire anaerobically. However, they are poisoned by high concentrations of oxygen. They gather in the upper part of the test tube but not the very top.
5: Aerotolerant organisms do not require oxygen as they metabolise energy anaerobically. Unlike obligate anaerobes however, they are not poisoned by oxygen. They can be found evenly spread throughout the test tube.


When an organism is able to survive in both oxygen and anaerobic environments, the use of the Pasteur effect can distinguish between facultative anaerobes and aerotolerant organisms. If the organism is using fermentation in an anaerobic environment, the addition of oxygen will cause facultative anaerobes to suspend fermentation and begin using oxygen for respiration. Aerotolerant organisms must continue fermentation in the presence of oxygen.


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

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

Oxygen is used during the oxidation of glucose and water is produced.[2]

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

See also


  1. ^ "aerobe" at Dorland's Medical Dictionary
  2. ^ a b c Hentges DJ (1996). "17: Anaerobes:General Characteristics". In Baron S. Medical Microbiology (4 ed.). Galveston, Texas: University of Texas Medical Branch at Galveston. Retrieved 24 July 2016.
  3. ^ a b c Kenneth Todar. "Nutrition and Growth of Bacteria". Todar's Online Textbook of Bacteriology. p. 4. Retrieved 24 July 2016.

Aerobic means "requiring air," in which "air" usually means oxygen.

Aerobic may also refer to

Aerobic exercise, prolonged exercise of moderate intensity

Aerobics, a form of aerobic exercise

Aerobic respiration, the aerobic process of cellular respiration

Aerobic organism, a living thing with an oxygen-based metabolism

Anaerobic organism

An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It may react negatively or even die if free oxygen is present. (In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenated environment.)

An anaerobic organism may be unicellular (e.g. protozoans, bacteria) or multicellular. For practical purposes, there are three categories of anaerobe: obligate anaerobes, which are harmed by the presence of oxygen; aerotolerant organisms, which cannot use oxygen for growth but tolerate its presence; and facultative anaerobes, which can grow without oxygen but use oxygen if it is present.

Aspergillus wentii

Aspergillus wentii is an asexual, filamentous, endosymbiotic fungus belonging to the mold genus, Aspergillus. It is a common soil fungus with a cosmopolitan distribution, although it is primarily found in subtropical regions. Found on a variety of organic materials, A. wentii is known to colonize corn, cereals, moist grains, peanuts and other ground nut crops. It is also used in the manufacture of biodiesel from lipids and is known for its ability to produce enzymes used in the food industry.

Congregibacter litoralis

Congregibacter litoralis KT71 is a gram-negative Gammaproteobacteria part of the NOR5/OM60 Clade discovered in seawater from Heligoland, an island in the North Sea by H. Eilers from the Max Planck Institute for Microbiology. C. litoralis KT71 is described as a pleomorphic bacterium and has a size of 2 x 0.5 μm. When grown in culture, C. litoralis KT71 has a generation time of 4.5 hours and prefers to grow on complex substrates where the sole carbon source is undefined, though it can utilize some sole carbon sources because they are most likely used by the organism for its central metabolism.

Endozoicomonas gorgoniicola

Endozoicomonas gorgoniicola is a Gram-negative and facultative anaerobic bacterium from the genus of Endozoicomonas. Individual cells are motile and rod-shaped. Bacteria in this genus are symbionts of coral. E. gorgoniicola live specifically with soft coral (family Gorgoniidae) and were originally isolated from a species of Plexaura, an octocoral, off the coast of Bimini in the Bahamas. The presence of this bacterium in a coral microbiome is associated with coral health.

Facultative anaerobic organism

A facultative anaerobe is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent.

Some examples of facultatively anaerobic bacteria are Staphylococcus spp., Streptococcus spp., Escherichia coli, Salmonella, Listeria spp. and Shewanella oneidensis. Certain eukaryotes are also facultative anaerobes, including fungi such as Saccharomyces cerevisiae and many aquatic invertebrates such as Nereid (worm) polychaetes.

Index of biology articles

Biology is the study of life and its processes. Biologists study all aspects of living things, including all of the many life forms on earth and the processes in them that enable life. These basic processes include the harnessing of energy, the synthesis and duplication of the materials that make up the body, the reproduction of the organism and many other functions. Biology, along with chemistry and physics is one of the major disciplines of natural science.

Leptospira noguchii

Leptospira noguchii is a gram-negative, pathogenic organism. L noguchii is famous for causing the febrile illness in Fort Bragg, NC during World War II. There was 40 cases of this fever documented during each summer from 1942 to 1944; however, there were 0 deaths recorded from this outbreak. Unlike other strains of Leptospira that cause leptospirosis, L. noguchii is characterized by showing a pretibial rash on the victim.

Methylophaga muralis

Methylophaga muralis is a species of Proteobacteria. It is capable of surviving in saline and alkaline environments and can obtain its carbon from methanol. This species was originally discovered in crumbling marble in the Moscow Kremlin; it has also been found in a soda lake in Buryatia.

Micrococcus roseus

Micrococcus roseus is a gram positive bacterial cell that grows in the tetrad arrangement. The normal habitat for this Micrococcus species is skin, soil, and water. It derives its name from the carotenoid pigment that it secretes. Isolated colonies on a TSA plate are circular, 1.0–1.5 mm in size, slightly convex, smooth, and pink in color. Optimal growth temperatures range from 25 to 35 degrees Celsius. Micrococcus roseus is a strictly aerobic organism.


Naegleria is a free living amoebae protist genus consisting of 47 described species often found in warm aquatic environments as well as soil habitats worldwide. It has three life cycle forms: the amoeboid stage, the cyst stage, and the flagellated stage, and has been routinely studied for its ease in change from amoeboid to flagellated stages. The Naegleria genera became famous when Naegleria fowleri, a human pathogenic strain and the causative agent of primary amoebic meningoencephalitis (PAM), was discovered in 1965. Most species in the genus, however, are non pathogenic.


In taxonomy, Natronococcus is a genus of the Halobacteriaceae.

Pseudomonas argentinensis

Pseudomonas argentinensis is a yellow-pigmented, Gram-negative, rod-shaped, nonspore-forming, strictly aerobic organism bacterium that infects the rhizospheres of Chloris ciliata and Pappophorum caespitosum, both grasses native to the Chaco region (Cordoba) of Argentina.

Pseudomonas denitrificans

Pseudomonas denitrificans is a Gram-negative aerobic organism bacterium that performs denitrification. It was first isolated from garden soil in Vienna, Austria. It synthesizes vitamin B12. Based on 16S rRNA analysis, P. denitrificans has been placed in the P. pertucinogena group.

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