[Unique properties of highly radioresistant bacteria].
In connection with the Chernobyl Nuclear Power Plant (ChNPP) accident and the negative ecological after-effects for biota in this zone the interest has arisen to radioresistant bacteria, as to the most dynamic model of the given ecosystem, and to mechanisms which provide resistance of bacteria to ionizing radiation. The analysis of published data has shown that the radioresistant bacteria are not interrelated taxonomically and phylogenetically. The extreme radioresistant bacteria are represented by the Deinococcus species, which form a group phylogenetically close to the line Thermus-Meiothermus. Other radioresistant bacteria are the representatives of the genera Rubrobacter, Methylobacterium, Kocuria, Bacillus and some archebacteria. Data on natural habitats, of radioresistant bacteria are not numerous. In a number of cases it is difficult to distinguish their natural habitats, as they were isolated from the samples which were previously exposed to X-ray or gamma-irradiation, or from the ecosystems with the naturally raised radioactivity. To understand the strategy of survival of radioresistant bacteria, we briefly reviewed the mechanism of action of various species of radiation on cells and macromolecules; physiological signs of the cell damage caused by radiation; mechanisms eliminating (repairing) these damages. More details on mechanisms of the DNA repair in D. radiodurans are described. The extreme resistance of D. radiodurans to the DNA damaging factors is defined by 1) repair mechanisms which fundamentally differ from those in other procaryotes; 2) ability to increase the efficiency of a standard set of the DNA repairing proteins. Literary and own data on the effect of radiation on survival of various groups of bacteria in natural ecosystems are summarized. The ecological consequences of the ChNPP accident for soil bacteria in this region were estimated. The reduction of the number of soil bacteria and recession of microbial diversity under the effect of anthropogenic radiation was shown.
Romanovskaia
V A
VA
Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, 154 Zabolotny St., Kyiv, 03143, Ukraine.
Rokitko
P V
PV
Malashenko
Iu R
IuR
D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000528:radiation effects*; D018407:Bacterial Physiological Phenomena / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D011210:Power Plants; D011839:Radiation, Ionizing; D018788:Radioactive Hazard Release; D012988:Soil Microbiology; D014455:Ukraine