“…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 (2,6,19,20,22,47,61,62,73 (5,19,26,52,61). Other ionizing-radiationresistant bacteria have been isolated and described; these include some species of the genera Acinetobacter, Chroococcidiopsis, Hymenobacter, Kineococcus, Kocuria, and Methylobacterium (4,5,11,23,24,30,49,50,53). Hyperthermophilic euryarchaeote species of the genera Thermococcus and Pyrococcus also contain ionizing-radiation-resistant strains (15,32,33).…”