Effects of Nanoselenium As a Nutrient Medium Component on the Main Cultivation Parameters and Antagonistic Activity of Lactobacillus Strains

The study aims to establish the effect of nanoselenium on the growth and antagonistic activity of the Lactobacillus casei IMB B-7343 and Lactobacillus plantarum IMB B-7344 strains against the phytopathogenic bacterium Xanthomonas campestris B-4102. Selenium nanoparticles were obtained by reducing a solution of sodium selenite with L-cysteine in the presence of sodium alginate. The cultivation of Lactobacilliwas carried out in a MRS nutrient medium with the addition of a colloidal solution of nanoselenium at the following concentrations: 0.05; 0.1; 0.15; 0.2 and 0.25 mg/l (for selenium). Bacteria were cultured in a 96-well plate in a Multiskan FC photometer at 36 ºС under constant shaking. The antagonistic activity of the strains was studied by the method of agar blocks. It was found that the addition of nanoselenium to the nutrient medium at a concentration of 0.2 to 0.25 mg/l contributed to a decrease in the duration of the exponential growth phase by an average of 3 hours, as well as to a decrease in the biomass accumulation of the L. casei IMB B-7343 strain by 15.0%. The optical density of this strain culture was observed to increase by 15.9% in the stationary growth phase under the addition of a nanoselenium solution to the nutrient medium at a concentration of 0.15 mg/l. During the cultivation of the L. plantarum IMB B-7344 strain in an MRS nutrient medium with the addition of a colloidal solution of nanoselenium at a concentration of 0.05–0.25 mg/l in the exponential development phase, an acceleration of the culture growth on average by 5 hours relative to the control was observed. It was noted that, upon the addition of nanoselenium to the nutrient medium, an increase in the antagonistic activity of lactobacillus strains against the phytopathogenic bacterium X. campestris B-4102 was observed, particularly in the L. plantarum IMB B-7344 strain (the zone of inhibition of the phytopathogen growth was 14.5–15 mm).