Antibacterial Effect of Nanocomposites Based on Nanoparticles of Chalcogens and Metals in Natural Polymer Matrices in Relation to the Phytopathogen Clavibacter sepedonicus

A summary of data on the antibacterial effect of nanocomposites (NCs) against the phytopathogenic bacterium Clavibacter sepedonicus (Cms) is presented. The NCs are obtained by chemical synthesis by immersing nanoparticles (NPs) in a natural polymer matrix. Both chalcogens: selenium and sulfur, and metal NPs: silver and manganese are used as NPs in the NCs. The natural polymer matrix for the NCs is polysaccharides: arabinogalactan (AG), starch, carrageenan, and polymers of a different nature, humic substances: therapeutic mud, coal, and shale obtained from various sources in Mongolia. In our studies, Se/AG NC has the most pronounced antibacterial activity against Cms. This NC has a pronounced bactericidal effect, reduces the growth of the bacterial suspension by increasing the number of dead cells in it, and has an antibiofilm effect. Studies using microscopy methods show that Se NPs attach to the surface of Cms causing cell deformation and its further destruction. The causes of such events could be changes in the fatty-acid composition of the bacterial cell under the influence of the NC, as well as deterioration in the functioning of dehydrogenases. NCs based on S NPs and Ag NPs do not have all the desired properties; they either reduce biofilm formation or have antimicrobial activity. The manganese-containing NCs have a pronounced biological effect against Cms only at increased concentrations. Thus, the data presented in this work allow us to consider NCs, especially Se/AG NCs, as an effective alternative to pesticides for regulating the number of phytopathogenic bacteria.