[The effect of gamma-radiation and desiccation on the viability of the soil bacteria isolated from the alienated zone around the Chernobyl Nuclear Power Plant].

Methylobacterium extorquens, M. mesophilicum, and Bacillus subtilis strains were found to be resistant to gamma-radiation, irrespective of whether they were isolated from the alienated zone around the Chernobyl Nuclear Power Plant or outside this zone. The LD90 of Methylobacterium and B. subtilis strains with respect to gamma-radiation was 2.0-3.4 and 3.7-4.4 kGy, respectively, whereas their LD99.99 values were 4.5-6.9 and more than 10 kGy, respectively. The high threshold levels of gamma-radiation for Methylobacterium and B. subtilis imply the efficient functioning of DNA repair systems in these bacteria. Unlike Bacillus polymyxa cells, the cells of M. extorquens, M. mesophilicum, and B. subtilis were also resistant to desiccation. Pseudomonas sp., Nocardia sp., and nocardioform actinomycetes were sensitive to both gamma-radiation and desiccation. Similar results were obtained when the bacteria studied were exposed to hydrogen peroxide and ultraviolet radiation. The results obtained indicate that the bacteria that are resistant to gamma-radiation are also resistant to desiccation, UV radiation, and hydrogen peroxide. The possibility of using simple laboratory tests (such as the determination of bacterial resistance to UV light and desiccation) for the evaluation of bacterial resistance to gamma-radiation is discussed.