ИСТИНА

Introduction The bacteria are able to produce volatile organic compounds (VOCs) that suppress growth of other microorganisms. Volatiles are considered to be able to play the significant role in antagonistic interactions between microorganisms occupying the same ecological niches. Aims To examine the antagonistic activity of Pseudomonas and Serratia strains provided by VOCs synthesis; to investigate the mechanisms of the regulation of the VOCs production; to identify VOCs emitted by these bacteria; to examine the action of the individual detected VOCs. Material and methods The effect of VOCs-producing bacterial strains against phytopathogenic strains of Agrobacterium tumefaciens, Erwinia carotovora, cyanobacteria Synechococcus and Anabaena and phytopathogenic fungi was tested using a dual-culture assay. Headspace solid-phase microextraction-gas chromatography-mass spectrometry was applied for VOCs identification. To investigate the mechanisms of the regulation of the VOCs production we studied the influence of mutations inactivated genes responsible for the global regulation of bacterial genes expression on VOCs synthesis. Results: VOCs produced by Pseudomonas and Serratia strains suppressed the growth of agrobacteria, E. carotovora, cyanobacteria and phytopathogenic fungi Rhizoctonia solani and Helminthоsporium sativum, caused changes in the morphology of the various fungi and mycelium degradation. It was found that mutations in genes rpoS, vfr, phzA, phzB of P. chlororaphis did not affect the VOCs production. VOCs emitted by P. chlororaphis 449 and several strains of Serratia were identified. The main headspace compounds were dimethyldisulfide, some ketones and alkenes. Strong inhibition of agrobacteria, cyanobacteria and fungi growth by these individual VOCs was observed. Conclusion: The production of the investigated compounds can be important for biological control of plant diseases by plant-associated bacteria. Keywords antagonistic interaction; bacteria; phytopathogenic fungi; volatile organic compound