Aerobic organism - Misplaced Pages

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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.

An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment. Facultative anaerobes grow and survive in an oxygenated environment and so do aerotolerant anaerobes.

Types

Obligate aerobes need oxygen to grow. In a process known as cellular respiration, these organisms use oxygen to oxidize substrates (for example sugars and fats) and generate energy.
Facultative anaerobes use oxygen if it is available, but also have anaerobic methods of energy production.
Microaerophiles require oxygen for energy production, but are harmed by atmospheric concentrations of oxygen (21% O₂).
Aerotolerant anaerobes do not use oxygen but are not harmed by it.

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

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

Yeast is an example of a facultative anaerobe, which can develop in the presence of oxygen but does not require it.

References

"aerobe" at Dorland's Medical Dictionary

Microbiology: Bacteria

Medical
microbiology

Biochemistry
and ecology

Oxygen preference	Aerobic Obligate Facultative Anaerobic Facultative Obligate Microaerophile Nanaerobe Aerotolerant
Other	Extremophile Human microbiome Gut Lung Mouth Skin Vaginal (in pregnancy) Placental Uterine Salivary Microbial metabolism Nitrogen fixation Microbial ecology Primary nutritional groups Substrate preference Lipophilic Saccharophilic

Shape

Structure

Cell envelope	Cell membrane Cell wall: Peptidoglycan NAM NAG DAP Gram-positive bacteria only: Teichoic acid Lipoteichoic acid Endospore Gram-negative bacteria only: Bacterial outer membrane Porin Lipopolysaccharide Periplasmic space Mycobacteria only: Arabinogalactan Mycolic acid
Outside envelope	Bacterial capsule Slime layer S-layer Glycocalyx Pilus Fimbria Non-motile bacteria
Composite	Biofilm

Taxonomy
and evolution

Categories:

Types

Glucose

Diversity

See also

References