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Development of biological preparations for organic agriculture should include the study of interactions of microorganisms-the components of biopreparations, with representatives of natural microbiota of agrocoenoses. As a microorganismtypical representative of epiphytic and soil microbiota, species Bacillus megaterium has been selected. Aim. The study of effect of Lactobacillus plantarum ONU 12 and Bacillus megaterium ОNU 484 on germination and growth of wheat seedlings. Materials and Methods. Seeds of wheat Triticum aestivum L. were inoculated with suspensions of bacteria B. megaterium ОНУ 484, L. plantarum ОНУ 12 and their mixture was germinated in hydroponics and soil under green house conditions. Germination of seeds, mean length of roots and height of seedlings were compared. Capability of these microorganisms to form biofilms was studied: inoculated seedlings were dyed with 0.1% acridin orange and observed with a magnification х600. Results. Simultaneous inoculation with bacteria L. plantarum ONU 12 and with the representatives of soil microbiota B. megaterium ОNU 484 didn't decrease the stimulation effect of lactobacilli. Opposite, the highest stimulation effect on plants both in hydroponics and in soil caused the treatments with the mixture L. plantarum ONU 12 + B. megaterium ONU 484 and with the strain B. megaterium ONU 484 alone. In hydroponics mean length of roots increased in 8.0-16.9%, mean height of seedlings-in 8.8-24.3%. In soil germination of seeds increased in 7.0%, mean height of seedlings-in 7.6%, mean root lengthin 13.1%. Lactobacilli and bacilli in the mixture were able to form biofilms with a developed matrix. Conclusions. In presence of representative of soil microbiota B. megaterium ONU 484 phytostimulation the activity of lactobacilli increased. Strain B. megaterium ONU484 also showed stimulation activity when applied separately.

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The aim of the study was to evaluate the effect of Bacillus megaterium ONU 500 on the germination and growth of sunflower seedlings. Materials and methods. Sunflower seeds were sown in containers with soil inoculated with a suspension of bacteria B. megaterium ONU 500 in concentration of 106 CFU/ml. After 21 days growth characteristics of seedlings were compared: germination, average height, root length, leaf area, dry weight. Effect of these microorganisms on biofilm formation on roots was investigated with light microscopy. Results. Inoculation of soil with B. megaterium ONU 500 resulted in the positive effect on roots length (increase by 21%), leaf area (increase by 22%) and dry weight of seedlings (increase by 17.8%). No significant effect on germination and plant height was observed. On the roots of plants grown in soil treated with B. megaterium ONU 500 more developed biofilms with well formed matrix were observed, which indicates the stimulation of ability of plant and soil microbiota to form biofilms in presence of bacilli from the studied strain. Conclusion. The investigations demonstrated that bacteria of B. megaterium ONU 500 strain caused a positive effect on development of sunflower seedlings and formation of biofilms on their roots.

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