This paper investigates the antagonistic and plant growth promotion activity of the new indigenous bacteria antagonist strains P. chlororaphis BZR 245-F and Pseudomonas sp. BZR 523-2. It was found that on the 10th day of cultivation, BZR 245-F and BZR 523-2 exhibit an antagonistic activity against F. graminearum at the level of 59.6% and 15.1% and against F. oxysporum var. orthoceras at the level of 50.2% and 8.9%, respectively. Furthermore, the BZR 523-2 strain stimulated the growth of winter wheat seedlings more actively than the BZR 245-F strain. When processing seeds of winter wheat, Pseudomonas sp. BZR 523-2 indicators were higher than in the control: plant height increased by 10.3%, and root length increased by 18.6%. The complex characteristic properties of the metabolite were studied by bioautography and HPLC-MS. Bioautography proved the antifungal activity of phenazine nature compounds synthesized by the new bacterial strains. We qualitatively and quantitatively analyzed them by HPLC-MS analysis of the strain sample metabolites. In the BZR 245-F sample, we found more phenazine compounds of various types. Their total phenazine concentration in the BZR 245-F was more than five times greater than in the BZR 523-2. We defined crucial differences in the quantitative content of the other metabolites. Despite the difference between new indigenous bacteria antagonist strains, they can be used as producers of effective biopesticides for sustainable agriculture management.

Особенности антагонизма бактерий рода Bacillus по отношению к токсиногенным грибам Fusarium при защите растений от болезни и контаминации микотоксинами (обзор)

The current knowledge on the prospects of using bacteria of the genus Pseudomonas as producers of effective microbiological preparations for the biocontrol of phytopathogenic organisms is summarized and analyzed. Rhizospheric pseudomonads are potential objects of agricultural biotechnology due to the presence of physiological and biochemical features necessary for biocontrol and phytostimulation. These features include tolerance to reactive oxygen species, chemotaxis in relation to root exudates, biosynthesis of siderophores and antibiotic metabolites of various nature. Members of the genus Pseudomonas are known for their great metabolic diversity, which allows them to colonize a wide range of ecological niches, including the rhizosphere. Pseudomonas species isolated from the rhizosphere have a broader catabolic activity than those isolated from the bulk soil, especially for certain sugars, polyols, and amino acids that can be found in root exudates. The wide metabolic diversity allows bacteria to become ubiquitous, forming protective biofilms and colonizing various ecological niches. At the same time, water-retaining capacity, fertility and porosity of the soil, as well as the conditions of mineral nutrition of plants are improved by increasing the availability of N, P, K and Fe. The paper describes in detail the main biologically active metabolites produced by Pseudomonas and their role in the suppression of phytopathogens and phytostimulation.

Currently, there is an active development of environmentally friendly methods of farming. However, the range of products for this type of farming system is limited. Growth stimulation is one of the mechanisms ensuring plant resistance to diseases that reduce crop yields. The aim of the work is to study the effect of laboratory samples of new biological products based on B. subtilis BZR 336 g, B. subtilis BZR 517, P. chlororaphis 245 F strains and organo-mineral fertilizers PRK White Pearl Brown (WPB) and PRK White Pearl Universal” (WPU) on plant growth and development of plants, as well as study of the possibility of their joint use for subsequent inclusion in organic farming systems or integrated plant protection. Growthpromoting ability was assessed in winter wheat and sunflower plants grown in sand in a climatic chamber. As comparison variants there were seed treatment with water (control), chemical (Dividend Star, KS) and biological (Fitosporin-M, F, B. subtilis 26 D) standards. In two plant cultures there was an expected retardant effect of the chemical standard and the growth-promoting effect of the biological standard. Statistically significant data were obtained for such a parameter as the shoot length. On winter wheat, laboratory samples provided the shoot length of 24.1-25.2 mm (an addition to the control of 3.4-8.2%), organic and mineral fertilizers - 23.9-24.5 mm (2.6-5.2%), mixtures with WPU - 23.2-24.4 mm (-0.4-4.7%), mixtures with WPB - 24.1-25.9 mm (3.4-11.2%), a significant increase in root length was not observed in this culture. On winter wheat, it is advisable to use the studied products separately. Sunflower is more responsive to the action of laboratory samples. They provided a shoot length of 13.6-14.6 mm (20.9-27.0%) and a root of 9.2-10.2 mm (4.5-15.9%). Organo-mineral fertilizers provided a shoot length of 14.2-14.5 mm (23.5-26.1%) and the root length of 10.8 mm (22.7%). Mixtures with WPU provided shoot length of 14.7-15.4 mm (27.8-33.9%), mixtures with WPB provided shoot length of 11.9-14.5 mm (3.5-26.1%), and no significant increase in root length was noted. The data obtained indicate the presence in the laboratory samples of fungicidal biological products growth-promoting properties, which vary depending on the culture and additionally used organic and mineral fertilizers. To confirm the results, additional experiments are necessary. Research in this direction will allow the rational use of the studied means of protection and increase plant yields in systems of organic, ecologized and integrated farming, and can help reduce the pesticidal pressure on agrocenoses.Conflict of interest: the authors stated that there was no conflict of interest.

Aim – to study the biocontrol properties of B. velezensis BZR 336g and B. velezensis BZR 517 strains against Fusarium pathogens using the fungus Fusarium graminearum as an example and to reduce the accumulation of deoxynivalenol (DON) and zearalenone (ZEN) in vitro.Materials and Methods. A study of the toxinogenicity of F. graminearum fungal strains was undertaken on rice and wheat grains and the effect of B. velezensis BZR 336g and B. velezensis BZR 517 strains on the growth of the fungus was studied on wheat grains and by the double cultures method. An experiment to study the effect of a liquid culture and supernatant of bacteria was carried out on wheat grains and the content of DON and ZEN in wheat grains was analyzed by HPLC and enzyme immunoassay.Results. It was found that two strains of the fungus F. graminearum were able to produce a high level of mycotoxins, while the strain F. graminearum 60318 had a higher growth rate. The B. velezensis BZR 336g and B. velezensis BZR 517 strains produced lipopeptide exometabolites and inhibited the growth of the F. graminearum 60318 strain. in vitro, while the content of ZEN remained at the control level.Conclusion. The ability of two strains of bacteria B. velezensis BZR 336g and B. velezensis BZR 517 to suppress the growth of the fungus F. graminearum 60318, as well as to inhibit the accumulation of mycotoxins in wheat grain in vitro, suggests that an increase in the content of antagonist bacteria B. velezensis BZR 336g and B. velezensis BZR 517 in the wheat microbiota can contribute to the suppression of the growth and harm of the fungus F. graminearum 60318.

Aim. To study the metabolomic profile of bacterial strains of the genus Bacillus promising for the development of biofungicides using thin layer chromatography (TLC), bioautography and high performance liquid chromatography with mass spectrometry (HPLC‐MS).Materials and Methods. The objects of study are strains of bacteria of the genus Bacillus. Exometabolites were isolated from the liquid culture and their metabolomic profile was analyzed by TLC, bioautography, and HPLC‐MS.Results. By the method of bioautography with a test culture of the fungus F. oxysporum var. orthoceras BZR F6 metabolites of bacterial strains of the genus Bacillus surfactin, iturin and fengycin were identified. Quantitative analysis using HPLC‐MS analysis allows us to state that the B. velenzensis BZR 336g and B. amyloliquefaciens BZR 277 strains produce more surfactin than the others. An increased content of ituric lipopeptides was found in strains B. velezensis BZR 517 and B. velenzensis BZR 336g. According to the ability to produce fengycins, strains of B. velezensis BZR 517 and B. velenzensis BZR 336g are ahead of other strains.Conclusion. Studies using two analytical methods reveal that the strains produce all three antifungal lipopeptides. This is important, since metabolites are able not only to suppress phytopathogenic fungi, but also to enhance the antifungal effect due to synergism. The results obtained allow us to state the possibility of using all four strains as producers of effective biofungicides.