Anaerobic organism

Jump to: navigation, search

WikiDoc Resources for Anaerobic organism

Articles

Most recent articles on Anaerobic organism

Most cited articles on Anaerobic organism

Review articles on Anaerobic organism

Articles on Anaerobic organism in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Anaerobic organism

Images of Anaerobic organism

Photos of Anaerobic organism

Podcasts & MP3s on Anaerobic organism

Videos on Anaerobic organism

Evidence Based Medicine

Cochrane Collaboration on Anaerobic organism

Bandolier on Anaerobic organism

TRIP on Anaerobic organism

Clinical Trials

Ongoing Trials on Anaerobic organism at Clinical Trials.gov

Trial results on Anaerobic organism

Clinical Trials on Anaerobic organism at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Anaerobic organism

NICE Guidance on Anaerobic organism

NHS PRODIGY Guidance

FDA on Anaerobic organism

CDC on Anaerobic organism

Books

Books on Anaerobic organism

News

Anaerobic organism in the news

Be alerted to news on Anaerobic organism

News trends on Anaerobic organism

Commentary

Blogs on Anaerobic organism

Definitions

Definitions of Anaerobic organism

Patient Resources / Community

Patient resources on Anaerobic organism

Discussion groups on Anaerobic organism

Patient Handouts on Anaerobic organism

Directions to Hospitals Treating Anaerobic organism

Risk calculators and risk factors for Anaerobic organism

Healthcare Provider Resources

Symptoms of Anaerobic organism

Causes & Risk Factors for Anaerobic organism

Diagnostic studies for Anaerobic organism

Treatment of Anaerobic organism

Continuing Medical Education (CME)

CME Programs on Anaerobic organism

International

Anaerobic organism en Espanol

Anaerobic organism en Francais

Business

Anaerobic organism in the Marketplace

Patents on Anaerobic organism

Experimental / Informatics

List of terms related to Anaerobic organism

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]


Overview

Aerobic and anaerobic bacteria can be identified by growing them in 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 anaerobic organism is any organism that does not require oxygen for growth and even dies in its presence.

  • Obligate anaerobes will die when exposed to atmospheric levels of oxygen.
  • Facultative anaerobes can use oxygen when it is present.
  • Aerotolerant organisms can survive in the presence of oxygen, but they are anaerobic because they do not use oxygen as a terminal electron acceptor.

Microaerophiles are organisms that may use oxygen, but only at low concentrations (low micromolar range); their growth is inhibited by normal oxygen concentrations (approximately 200 micromolar). Nanaerobes are organisms that cannot grow in the presence of micromolar concentrations of oxygen, but can grow with and benefit from nanomolar concentrations of oxygen.

Obligate anaerobes may use fermentation or anaerobic respiration. In the presence of oxygen, facultative anaerobes use aerobic respiration; without oxygen some of them ferment, some use anaerobic respiration. Aerotolerant organisms are strictly fermentative. Microaerophiles carry out aerobic respiration, and some of them can also do anaerobic respiration.

There are many chemical equations for anaerobic fermentative reactions.

Fermentative anaerobic organisms mostly use the lactic acid fermentation pathway:

C6H12O6 + 2 ADP + 2 phosphate → 2 lactic acid + 2 ATP

The energy released in this equation is approximately 150 kJ per mol, which is conserved in regenerating two ATP from ADP per glucose. This is only 5% of the energy per sugar molecule that the typical aerobic reaction generates.

Plants and fungi (e.g., yeasts) generally use alcohol (ethanol) fermentation when oxygen becomes limiting:

C6H12O6 + 2 ADP + 2 phosphate → 2 C2H5OH + 2 CO2 + 2 ATP

The energy released is about 180 kJ per mol, which is conserved in regenerating two ATP from ADP per glucose.

Anaerobic bacteria and archaea use these and many other fermentative pathways, e.g., propionic acid fermentation, butyric acid fermentation, solvent fermentation, mixed acid fermentation, butanediol fermentation, Stickland fermentation, acetogenesis or methanogenesis.

Some anaerobic bacteria produce toxins (e.g., tetanus or botulinum toxins) that are highly dangerous to higher organisms, including humans.

Obligate (strict) anaerobes die in presence of oxygen due to the absence of the enzymes superoxide dismutase and catalase which would convert the lethal superoxide formed in their cells due to the presence of oxygen.

See also



ca:Anaeròbic cs:Anaerobní da:Anaerob de:Anaerobie eo:Anaeroba organismo id:Organisme anaerobik it:Anaerobiosi he:אל-אווירני mk:Анаероб nl:Anaeroob no:Anaerob simple:Anaerobic organism fi:Anaerobinen eliö sv:Anaerob uk:Анаероби


Linked-in.jpg