Microorganism
A microorganism or microbe is a living thing (organism) that is too small to be visible to the human eye (microscopic). The study of microorganisms is called microbiology.
Microorganisms can be bacteria, fungi, archaea or protists. Some microbiologists also include viruses, but others consider these as non-living.[1][2][3]
Most micro-organisms are single-celled, or unicellular organisms, but there are unicellular protists that are visible to the human eye, and some multicellular species are microscopic.
Microorganisms live almost everywhere on earth where there is liquid water, including hot springs on the ocean floor and deep inside rocks within the earth's crust. Such habitats are lived in by extremophiles.
Microorganisms are critical to nutrient recycling in ecosystems, because they act as decomposers. Because some microorganisms can also take nitrogen out of the air, they are an important part of the nitrogen cycle. Pathogenic, or harmful, microbes can invade other organisms and cause disease.
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[change] Free-living microorganisms
Free-living microbes get their energy in many different ways. Some use photosynthesis, like plants do. Some break down natural chemicals in their environment. Others feed on things that were once living, such as fallen leaves and dead animals, causing them to breakdown or decay. The decayed materials mix with soil, providing essential nutrients for plants to use. Without this process, the nutrients in the soil would run out. These types of organisms are called decomposers. They are the natural recyclers of living things on our planet. Microbes also help us make some of our foods, such as bread, cheese, yogurt, beer, and wine. They feed on the sugar in grain, fruit, or milk, giving these foods a special texture and taste. [4]
[change] Parasitic microbes
Some microbes, often called germs, cause illness or disease. They are parasites which live by invading living things. Chickenpox, mumps, and measles are caused by these germs.[4] They are infectious diseases. Some microbes can cause food to decay. Moldy bread or fruit, sour milk, and rotten meat are examples of decayed food. If eaten, this rotten food and drink can cause stomach upsets. Other microbes cause tooth decay.[4] You can protect yourself from harmful microbes by storing and preparing food properly, cleaning your teeth, washing your hands, and by avoiding close contact with ill people.[4]
[change] Other websites
- Microbe News from Genome News Network
- BBC News, 28 September, 2001: The microbes that 'rule the world' Citat: "... The Earth's climate may be dependent upon microbes that eat rock beneath the sea floor, according to new research....The number of the worm-like tracks in the rocks diminishes with depth; at 300 metres (985 feet) below the sea floor, they become much rarer..."
- BBCNews: 16 January, 2002, Tough bugs point to life on Mars Citat: "...This research demonstrates that certain microbes can thrive in the absence of sunlight by using hydrogen gas..."
- BBCNews: 17 January, 2002, Alien life could be like Antarctic bugs
- Microbiology
- Microbe fixes nitrogen at a blistering 92 C
[change] References
- ↑ Rybicki EP (1990). "The classification of organisms at the edge of life, or problems with virus systematics". S Aft J Sci 86: 182–6. ISSN 0038-2353.
- ↑ Lwoff A (1957). "The concept of virus". J. Gen. Microbiol. 17 (2): 239–53. PMID 13481308.
- ↑ Forterre P. 2010 Defining life: the virus viewpoint. Orig Life Evol Biosph. 40(2):151-60. [1]
- ↑ 4.0 4.1 4.2 4.3 Blue Planet. McGrawHill. 2003.
