The Influence of the Conditions of Cultivation of Lactic Acid Bacteria on Their Antagonistic Activity Against Some Plant Pathogenic Bacteria.

Plant diseases caused by pathogenic microorganisms result in significant damage to agriculture. Lactic acid bacteria (LAB), in particular strains of (), are used as one of the biocontrol methods against plant pathogenic bacteria due to high antagonistic activity associated with their metabolic potential. We have investigated the influence of nutrient medium components (various carbon and nitrogen sources) and cultivation conditions (temperature, duration, and pH) of strains on the level of their antagonistic activity against the test strains of plant pathogenic bacteria. The antimicrobial activity of LAB supernatants was maximal in the presence of 3% (30 g/L) sucrose as the main carbon source and 1% (10 g/L) tyrosine as the main nitrogen source in the nutrient medium against all investigated test strains of PPB. However, the use of such a carbon source as galactose or arabinose led to a decrease or even absence of antimicrobial properties of LAB against phytopathogenic bacteria. The optimal conditions for cultivation of lactobacilli were determined: cultivation temperature +30 ± 1°C, pH 7.8, and duration 72 h. Strains of and caused zones of inhibition in test pathogens from 298 to 291 mm. Whereas during 24-h cultivation of LAB strains, their antagonistic activity was significantly lower, and the zones of inhibition decreased by 30%. The duration and temperature had a significant effect on increasing the antagonistic activity of strains, in contrast to the pH of the medium ( ≥ 0.05).