ANTAGONISTIC ACTIVITY OF BLACK SEA ACTINOBACTERIA AGAINST PHYTOPATHOGENIC MICROORGANISMS

The biological method of plant protection is an environmentally safe and priority form in long-term programs to combat pathogens and one of the important tools for the transition to organic and ecological agriculture in Ukraine. Aim. To define the antagonistic activity of the Black Sea actinobacteria against phytopathogenic microorganisms. Methods. The antagonistic activity of 35 strains of actinobacteria isolated from different biotopes of the Odesa Bay of the Black Sea against collection and isolated from affected cereal plants phytopathogenic microorganisms was determined by the block method after preliminary cultivation of actinobacteria on Gause 2 medium for 12 days at 28±1 °C. The antagonistic activity of extracted secondary metabolites of Streptomyces ambofaciens ONU 1016 and S. ambofaciens ONU 561 against Fusarium oxysporum strains was determined by the disk-diffusion method. Results. Of the 35 studied, the growth of at least one strain of phytopathogenic bacteria and fungi was inhibited by 77.1% and 65.7% of actinobacterial strains, respectively. The sizes of the zones of no growth of sensitive collection strains of bacteria ranged from 15.3±0.1 mm to 29.6±0.3 mm, and of bacterial strains isolated from affected plants – from 14.5±0.1 mm to 25.7±0.3 mm under the action of antagonistically active actinobacteria. This indicator for collection strains of fungi was determined in the range from 16.0±0.2 mm to 33.5±0.3 mm, for isolated strains of fungi – from 15.0±0.1 mm to 29.3±0.3 mm. S. ambofaciens ONU 1016 and S. ambofaciens ONU 561 showed the best activity against all strains of phytopathogenic microorganisms, in particular against F. oxysporum isolated from affected plants, the zones of no growth of more than 80.0% of the strains of which exceeded 20.0 mm. The extracted secondary metabolites of both S. ambofaciens strains inhibited the growth of the collection and isolated fusarium strains. The zones of no growth of fungi varied widely and depended, primarily, on the strains of fusarium, streptomyces, the concentration of extracts, and the period of recording the results. The minimum inhibitory concentrations of extracted metabolites of S. ambofaciens ONU 1016 and S. ambofaciens ONU 561 against the isolated strains of F. oxysporum were 250 μg/ml – 500 μg/ml and 250 μg/ml – 100 μg/ml, respectively. Conclusions. Actinobacterial strains isolated from sponges and mussels of the Odesa Bay of the Black Sea are antagonistically active against phytopathogenic microorganisms, in particular the fungi F. oxysporum. Collection strains of phytopathogens are more sensitive to the action of sea actinobacteria than strains isolated from affected plants. Strains S. ambofaciens ONU 1016 and S. ambofaciens ONU 561, which showed high antagonistic activity, can be recommended for the creation of a microbial preparation for protecting plants from bacterial and fungal pathogens.