Research on Streptomycetes from Moldovian soils with antifungal, nematicidal and phytostimulating activity on tomato

Aim. The purpose of the research was to determine the antifungal, nematicidal and phytostimulating activity of streptomycetes isolated from the soil of Moldova. Methods. The strains were stored on the media Czapek and oatmeal agar by subculturing. Antifungal activity was determined by disk diffusion method, using phytopathogenic fungi as test cultures. To determine the nematicidal and phytostimulating activity of exometabolites of the studied strains, they were cultivated on complex medium M-I and aqueous solutions of exometabolites (EM) were prepared that were contained in the liquid culture after it was separated from the biomass by centrifugation. Tomato seeds were treated by soaking in EM solutions and the germination and length of the roots were determined. Nematicidal activity was determined by mortality test. Results. Strains that completely inhibited the growth of A. alternata, B. cinerea and S. solani (S. sp. 9, 10 and 17) or retarded the growth of test cultures to different degrees (zone diameters from 25.0 to 34.0 mm) were found. For nematicidal activity, the best results were shown by EM strains of S. spp. 9 and 205. The best results on the germination of tomato seeds of the cv. Fakel were obtained by treating with a 0.5% solution of EM strains of S. spp. 49 and 154 (by 11.32% more than in control), and for root growth - of EM of all strains (73-89% more than in control). Conclusions. Studies have shown that the EM of streptomycetes isolated from the soil of Moldova can be used to obtain new plant growth stimulants and biopesticides.