Оценка встречаемости полиауксотрофных вариантов аммонифицирующих бактерий в пробах почв, находившихся в условиях длительного воздействия ионизирующего излучения

Abstract

This paper presents the results of an assessment of the occurrence of polyauxotrophic variants of ammonifying bacteria in soil samples exposed to prolonged exposure to ionizing radiation. Soil sampling was carried out on model plots (25 m 2 each) of the territory of the Polessky State Radiation and Ecological Reserve (PGREZ) and the Berezinsky Biosphere Reserve (BBZ) (natural background level of ionizing radiation). Polyauxotrophic variants were identified by their inability to grow on a minimal agarized medium and the need for five or more growth factors (amino acids: leucine, proline, serine, cysteine, tyrosine, glutamic acid, histidine, arginine, lysine, methionine). It was revealed that polyauxotrophic forms of ammonifying bacteria are found in all samples of the studied soils. The minimum number of polyauxotrophic forms was found among B. mycoides and BGCP strains isolated from soil BBZ – 10 (8.25 ÷ 11.5) %, p < 0.05. The maximum amount of polyauxotrophy was recorded in B. cereus strains isolated from PGREZ – 95 soils (92.25–97.75) %, p < 0.05. The dependence of the percentage of occurrence in soil microsociety of polyaxotrophic variants of the bacterium of the genus Bacillus and BGCP on the level of background radiation was noted. A proposal was also put forward to include the obtained data in the development of a bioindication system of test microbiological indicators to assess the state of Belarusian landscapes, since they allow an objective assessment of the steppe of anthropogenic pollution.