Investigation of the effect of prolonged nuclear radiation on the aboriginal bacterial populations in the zone of the Chernobyl atomic power station catastrophe

Informacje na temat projektu

Identyfikator umowy o grant: INTAS-94-2825

Data rozpoczęcia 1 Czerwca 1995

Data zakończenia 31 Maja 1997

Finansowanie w ramach

• International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993-

Koszt całkowity € 0,00

Wkład UE € 20 000,00

Koordynowany przez

Max-Planck Gesellschaft zur Förderung der Wissenschaften e.V.
Germany

Exploitable results

Investigation of the effect of prolonged nuclear radiation on the aboriginal bacterial population in zone of the Chernobyl atomic power station catastrophe

The accident at the Chernobyl Atomic Power Station (ChAPS) in1986 has created a natural model for studying the consequences of prolonged ionizing radiation effect (1-128 µCi/kg of soil) on microorganisms as apart of the biota of a radioactively extremely polluted region (10 km ChAPSzone). It was shown, that in soils of the 10 km ChAPS zone subjected for long duration radiation treatment the species diversity indices of heterotrophic bacteria were very low in comparison with that in unpolluted soils. Dominant species among heterotrophic bacteria was Bacillus cereus. In all soil samples pink pigmented facultative methylotrophic (PPFMs) bacteria Methylobacterium extorquens or Methylobacterium mesophilicum have been found. The frequency of occurrence and species structure of PPFMs in soil and plant samples within the 10 km ChAPS zone did not differ essentially from those in similar samples collected outside the zone. Isolated strains of genera Bacillus and Methylobacterium displayed high resistance to hydrogen peroxide, which act to a certain extent similarly to ionizing radiation. Other species of heterotrophic bacteria were present not in all soil samples of the 10 km ChAPS zone and they were characterized by low resistance toH2O2. The PPFM strains isolated from the ChAPS zone were characterized by higher activity of superoxide dismutase (SOD). Bacillus strains isolated from unpolluted samples had the same level of activities of SOD and catalase as the majority of strains of the same species isolated from the 10km ChAPS zone. Apparently, antioxidant enzymes may really play a role in protection of cells during irradiation. It was found, that in soils of the 10 km ChAPS zone the number cellulose fermenting, nitrifying and sulfate reducing bacteria was lower by an order of magnitude, than in similar control soils. These results indicated the decrease of number and diversity of soil bacteria under anthropogenic radiation. The level of genetic variability of PPFMs was higher instrains, isolated within the 10 km ChAPS zone. PPFMs were highly resistant to UVand ionizing irradiation. UV had only a low mutagenic effect on PPFMs. The dozes of nuclear radiation less 0.6 kGy did not have influence on a viability of investigated PPFM strains. The sublethal dozes were 5-10 kGy for some strains. Apparently, PPFMs possess elevated capabilities to repair radiation damage which enable them to survive under high radiation level. Thus, the selective pressure of long duration treatment of nuclear radiation on soil bacteria was displayed as change of their qualitative and quantitative structure. Constant inhabitants of all investigated radioactively polluted soils were Bacillus cereus, and also Methylobacteriumextorquens or M. mesophilicum, which must possess active mechanisms of detoxication of the active oxygen species and/or of DNA damage repair system.