Microorganisms represent major life forms on earth and thus the most important components of biodiversity of the planet. Bacteria and Archaea have been living on earth for more than 3 Billion years and shaped the enviornment for evolution of other life forms.
They move global cycles of C,O,N,P. They compost and mineralize,thus keep the enviornment clean.Increasingly they are being used as biofertilizers and biopesticides. They are, therefore, important for the health of the planet. They are a rich source of health supporting chemicals pencillin, stretomycin,cyclosporin, streptokinase and many other therapeutic agents are derived from microbes. A large number of foods ( Curd,Cheese etc.) rely on their activities.Only a few of them are really nasty pathogen to human, animals and plants.
WHAT ARE MICROBES ?
These are the organisms too small to be seen by naked eye. One has to use a microscope to see them. These include both prokaryotic (genetic material, DNA is not organised in a nucleus and no organelle)archaea and bacteria as well as eukaryotic(DNA is organised as chromosomes in a nucleus) organisms like fungi, yeasts, protozoa, micro algae etc. Viruses are much smaller than bacteria and they are active only when they are inside a host organism.
WHERE DO WE FIND THEM ?
Microbes, specially bacteria are present every where - in the air, in water, soil,in extreme habitats like icy continent,hydrothermal vents(temperature may be above 100 C), sea sediments etc. They are present on and in other living organisms. For example, one gram of soil contains about a million bacteria, human skin has approximately a thousand bacteria per sqaure inch and colon has about 10 trillion. Microbes present in extreme enviornments are mostly members of archaea group. Fungi are also present everywhere but not in extreme enviornments. Tropical rain forests are rich habitats for a large number of fungi. Algae are found in moist places and in aquatic bodies.Many microbes live in association with other organisms, sometimes deriving mutual benefit (symbiotic) or as parasites. Microbes are the unseen majority on this planet.
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