Introduction. Iron is one of the most important essential elements for all living organisms and one of the most common metals in the earth's crust and soils. The aim of the work: to evaluate the biological activity of iron chelate complexes obtained by the method of targeted bacterial synthesis based on soil isolates of Bacillus sp., in relation to bacteria, fungi and higher plants. Material and methods. Soil samples taken near quarries of non-ferrous and ferrous metallurgy mining enterprises (quarry of PJSC Gaisky Mining and Processing Plant, quarry and "blue" lake of the Blyavinsky copper-pyrite deposit of OOO MMSC, Orenburg region) served as a source of metal-resistant strains of Bacillus sp. The diffusion method of agar wells, serial dilutions, "replicas" were used, phytotesting was carried out in accordance with ISO 11269-2:2012 and GOST 12038-84. Results. The obtained in the process of one-stage interaction of the destructured biomass of the B. cereus sample Cu pit with a solution of FeSO47H2O (precursor) at a concentration of 0.125 M in a ratio of 1:10 has a high potential for use as a bactericidal complex characterized by a pro-nounced inhibitory effect on S. aureus and P. aeruginosa (p < 0.01). In a model experiment on Triticum aestivum and Sinapis alba, a reliably significant stimulation of the formation of chlorophyll a and b of both test cultures and an increase in compensatory mechanisms with an increase in their stress resistance were recorded. The study of fungicidal activity of test samples of biomaterial B. cereus Cu pit in combination with FeSO47H2O 0.250 M completely suppresses the growth of the studied fungi. Conclusions. The potential for using chelate complexes based on the iron-resistant strain B. cereus Cu pit is due to the level of its biological activity depending on the concentration of the introduced precursor.
