1. Wprowadzenie. 1.1. Promieniowanie oraz jego wpływ na organizmy żywe. 1.2. Drobnoustroje radiotolerancyjne – definicja, teorie na temat pochodzenia, oporność na promieniowanie. 2. Charakterystyka wybranych organizmów radiotolerancyjnych. 2.1. Bakterie. 2.2. Archeony. 2.3. Grzyby mikroskopowe. 3. Podsumowanie
Abstract: Ionizing radiation damages DNA, proteins and lipids in cells in a direct (10–20% DNA damage) and indirect manner (80–90%) – causing water radiolysis and a redox potential increase (oxido-reductive stress). For instance, hydrogen peroxide and ozone are generated. Hydroxyl radical (OH.) is the most reactive and harmful reactive oxygen species (ROS). Radiotolerant microorganisms are extremophilic microbiota, sustaining high doses of radiation in a vegetative state. One of the most resistant and extensively studied species is Deinococcus radiodurans. This bacterium can reconstitute its genome shattered to dozens of fragments (double strand breaks) as a result of the exposure to radiation or dessication. Other examples include: bacteria: Acinetobacter radioresistens, Rubrobacter radiotolerans, Kineococcus radiotolerans, Ralstonia sp. and Burkholderia sp. (living in biofilm communities from spent fuel pools); archaea: Thermococcus gammatolerans; diverse microscopic, often melanized, presumably radiotropic fungi, e.g. Cladosporium spp., from the surrounding of the destroyed Chernobyl power plant. Many of such organisms can be found in desert areas as they are dehydratation-tolerant. Radioresistant species can be potentially utilized for bioremediation of radioactive environment contamination and for nuclear waste management (e.g. bioprecipitation, biosorption, bioaccumulation of uranium or other radioisotopes). For example, diverse molds isolated from the Chernobyl region can be used for mycoremediation due to their ability to decompose contaminated organic matter, adsorb, converse into a soluble form and accumulate radionuclides (e.g. caesium 137).
1. Introduction. 1.1. Radiation and its effect on organisms. 1.2. Radiotolerant microorganism – definition, theories about their origin, radioresistance. 2. Description of selected radiotolerant species 2.1. Bacteria. 2.2. Archaea. 2.3. Microfungi. 3. Summary