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Radioresistant and Dessication Resistant Organisms: Their Habitat...

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Radioresistant and Dessication Resistant Organisms: Their Habitat, Mechanism of Adaptations and Biotechnological Applications

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  • December 2012
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INTRODUCTION
Radiations are energy in the form of waves or particles. They are of two forms, ionizing radiations and non-ionizing radiations. Ionizing radiations are radiations of short wavelength and high energy which causes atoms to ionize. Examples of ionizing radiations includes: x-rays, gamma rays, ultra violet radiation. Non-ionizing radiations are radiations of long wavelengths and low energy. Examples of non ionizing radiations includes infra-red rays and visible lights e.t.c Effects of ionizing radiations on organisms are extreme which includes: mutations, breakage of hydrogen bonds, oxidation of double bonds, polymerization of some molecules, generation of radicals like singlet oxygen and OH radicals, formation of thymine dimmers, breakage of tryptophan into toxic photoproducts .the most lethal effect of ultra violet radiation is that its wavelengths can be absorbed by the DNA (deoxyribonucleic acid) of most microbial cells. These effects are dangerous to a cell and nearly all cells do not survive exposures to radiation but a particular organism we are considering radioresistant organisms a group of extremophiles survive these condition and not only survive these conditions but also thrive. Examples of these organisms include:

Extreme ionizing-radiation resistance has been observed in several members of the domains; Bacteria and Achaea. Of the genera containing ionizing-radiation resistant organisms, Deinococcus and Rubrobacter show the highest levels of resistance, and all species of these genera have been shown to be either gamma radiation resistant or UV radiation resistant or both. Microorganisms of the genus Deinococcus, which Include D. radiodurans is the type species of this genus, and the best studied member. All known members of the genus are radioresistant: D. proteolyticus, D. radiopugnans, D. radiophilus, D. grandis, D. indicus, D. frigens, D. saxicola, D. marmoris, D. deserti,D. geothermalis and D. murrayi; the latter two are also...