SENSITIVITY OF PURE CULTURES OF BRADYRHIZOBIUM JAPONICUM TO FUNGICIDES

Objective. Conduct screening of a wide variety of transgenic mutagenesis strains of Bradyrhizobium japonicum nodule bacteria by the sensitivity to Fever, Standak Top, Akanto Plus, Maxym XL, and Benorad fungicides, and obtain Tn5 mutants resistant to different normal rates of the above pesticides. Methods. Microbiological, statistical. Results. Under the conditions of laboratory experiments, Tn5 mutants of B. japonicum, resistant to the production and dual production normal rate of Fever, Standak Top, Akanto Plus, Maxym XL, and Benorad, were selected. It was shown that the active substances of the products with fungicidal activity Fever, Standak Top, Akanto Plus, Maxym XL do not have bactericidal effect on cell viability of the majority of Tn5 mutants obtained as a result of intergeneric conjugation between Escherichia coli S17-1 with different plasmid vectors and strains of B. japonicum 646 and 634b, and only in some cases reduce the intensity of their reproduction. It was established that Tn5 mutants of B. japonicum under study have different sensitivity to the influence of the normal rates of benomil-based Benorad recommended by the manufacturer and twice-increased. Nine Tn5 mutants were evaluated as low-sensitive to the production normal rate of Benorad, 11 were characterized by a higher sensitivity to fungicide, as evidenced by the zones of delayed growth of bacterial lawn around wells with the product over 15 mm. The influence of the double Benorad normal rate on transposon mutants was significantly stronger compared with other fungicides. Three Tn5 mutants, low-sensitive to the influence of the double rate of this product were selected, and delay of the reproduction of cells in these variants of the experiment was 14-15 mm around the wells. Conclusion. The use of bacterial fertilizers for soybeans based on Tn5 mutants of B. japonicum resistant to modern fungicides will help to reduce the consequences of chemical stress on the formation and functioning of symbiotic systems.