title: Survival of thermophilic and hyperthermophilic microorganisms after exposure to UV-C, ionizing radiation and desiccation.
abstract: In this study, we investigated the ability of several (hyper-) thermophilic Archaea and phylogenetically deep-branching thermophilic Bacteria to survive high fluences of monochromatic UV-C (254 nm) and high doses of ionizing radiation, respectively. Nine out of fourteen tested microorganisms showed a surprisingly high tolerance against ionizing radiation, and two species (Aquifex pyrophilus and Ignicoccus hospitalis) were even able to survive 20 kGy. Therefore, these species had a comparable survivability after exposure to ionizing radiation such as Deinococcus radiodurans. In contrast, there was nearly no difference in survival of the tested strains after exposure to UV-C under anoxic conditions. If the cells had been dried in advance of UV-C irradiation, they were more sensitive to UV-C radiation compared with cells irradiated in liquid suspension; this effect could be reversed by the addition of protective material like sulfidic ores before irradiation. By exposure to UV-C, photoproducts were formed in the DNA of irradiated Archaea and Bacteria. The distribution of the main photoproducts was species specific, but the amount of the photoproducts was only partly dependent on the applied fluence. Overall, our results show that tolerance to radiation seems to be a common phenomenon among thermophilic and hyperthermophilic microorganisms.
authors.affiliation: Radiation Biology Division, Institute of Aerospace Medicine, German Aerospace Center (DLR e.V.), Linder Hoehe, 51147 Cologne, Germany. kristina.beblo@dlr.de
authors.forename: Kristina
authors.initials: K
authors.lastname: Beblo
authors.forename: Thierry
authors.initials: T
authors.lastname: Douki
authors.forename: Gottfried
authors.initials: G
authors.lastname: Schmalz
authors.forename: Reinhard
authors.initials: R
authors.lastname: Rachel
authors.forename: Reinhard
authors.initials: R
authors.lastname: Wirth
authors.forename: Harald
authors.initials: H
authors.lastname: Huber
authors.forename: Günther
authors.initials: G
authors.lastname: Reitz
authors.forename: Petra
authors.initials: P
authors.lastname: Rettberg
mesh_terms: D001105:Archaea / Q000235:genetics / Q000528:radiation effects*; D001419:Bacteria / Q000235:genetics / Q000528:radiation effects*; D004249:DNA Damage; D019641:DNA, Archaeal / Q000032:analysis; D004269:DNA, Bacterial / Q000032:analysis; D003890:Desiccation; D050296:Microbial Viability; D011836:Radiation Tolerance; D011839:Radiation, Ionizing; D013045:Species Specificity; D014466:Ultraviolet Rays
chemical_list: D019641:DNA, Archaeal; D004269:DNA, Bacterial