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Name: KARTHi
Status: student
Grade: n/a
Location: N/A
Country: India
Date: Fall 2012

I read today that archaea live in human colon. What is the function of it in human body?

Many of the archaea in the human digestive tract are what is called 'methanogens', or microorganisms that produce methane. The main species scientists have found there is called Methanobrevibacter smithii. The primary role of methanogens in human digestion is related to bacterial fermentation. Bacteria (not archaea) in the gut use fermentation to break down the food we eat, releasing many more nutrients for absorption in the intestines. This fermentation process produces excess hydrogen. If the hydrogen were to build up in our gut, bacterial fermentation would slow and we would end up receiving less nutrition/energy from the food we eat. Methanogens are able to consume this excess hydrogen (and carbon dioxide) and release methane (and water), which in turn enhances the efficiency of bacterial fermentation. Thus, archaea in the gut are a crucial part of our ability to extract useful nutrients and energy from our food.

S. Unterman Ph.D.


Here is a very informative article on Archaea. It even has pictures.

You can find out more about Archaea by going to and searching for “Archaea.. If you don’t understand any of the blue words, you can click on them and that will take you to an explanation of that word.

Here are some points from the Wikipedia article:

The Archaea…constitute a domain of single-celled microorganisms. These microbes have no cell nucleus or any other membrane-bound organelles within their cells.

The Archaea…are now classified as a separate domain in the three-domain system

Archaea and bacteria are quite similar in size and shape, although a few archaea have very strange or unusual shapes, such as the flat and square-shaped cells of Haloquadratum walsbyi

Initially, archaea were seen as extremophiles that lived in harsh environments, such as hot springs and salt lakes, but they have since been found in a broad range of habitats, including soils, oceans, marshlands and the human colon.

Archaea are particularly numerous in the oceans, and the archaea in plankton may be one of the most abundant groups of organisms on the planet. Archaea are now recognized as a major part of Earth's life and may play roles in both the carbon cycle and the nitrogen cycle. No clear examples of archaeal pathogens or parasites are known, but they are often mutualists or commensals. One example is the methanogens that inhabit the gut of humans and ruminants, where their vast numbers aid digestion. Methanogens are used in biogas production and sewage treatment, and enzymes from extremophile archaea that can endure high temperatures and organic solvents are exploited in biotechnology.

Sincere regards, Mike Stewart

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