Antimicrobial activity of exometabolites of Paenibacillus polymyxa, isolated from endophytic community of winter wheat grain

Abstract

In preliminary studies, a strain Paenibacillus polymyxa P6 possessing multiple plant growth-promoting (phosphate solubilization, oligonitrotrophy and production of heteroauxins) and antagonistic activities was isolated from grainresided cultivable bacterial endophytic community of winter wheat variety of the domestic selection Podolyanka with increased resistance to the causative agent of basal bacteriosis of grain crops Pseudomonas syringae pv. atrofaciens. The aim of this work was to study the antimicrobial effect of the exometabolites, produced by isolated strain, towards gram-negative phytopathogenic microorganisms using the method of deferred antagonism under the condition of cultivating the antagonistsc bacterium for 72 and 120 hours before inoculation of test cultures. Microorganisms stored in the collection of the D.K. Zabolotny Institute of Microbiology and Virology, NAS of Ukraine: Ralstonia solanocearum B-1109, Pectobacterium carotovora subsp. carotovora B-1077, Pseudomonas syringae pv. syringae B-1022, Pseudomonas syringae pv. syringae van Hall 1902 B-1027, Pseudomonas syringae pv. atrofaciens B-1011, Pseudomonas syringae pv. atrofaciens B-1013, as well as Erwinia amylovora ATCC 15580 were used as a test-cultures. Paenibacillus polymyxa P6 exometabolites were found to have a dose-dependent antimicrobial effect towards all studied microorganisms. The most pronounced inhibitory effect was registered against Erwinia amylovora ATCC 15580, Pseudomonas syringae pv. syringae B1022 and Ralstonia solanocearum B-1109: the diameter of the zone of no growth under the action of exometabolites produced for 120 hours are 25.72 ± 4.0 mm, 22.93 ± 2.0 mm and 20.30 ± 4.0 respectively. These results substantiate the expediency of further investigation of the composition and biological activity of the studied exometabolites in the perspective of developing biotechnological preparations.