Sensitivity of bees’ pathogenic bacteria to a sample of copper solution and silver citrate

Abstract

The article presents the studies’ results of the experimental disinfectan’s antimicrobial effect on microorganisms of various morphological groups that currently cause bees’ enterobacteriosis. For work, we used cultures of bee enterobacteria: a pure microorganisms culture of the species Klebsiella pneumoniae and natural (mixed) strains of enterobacteria excreted from sick bee colonies at apiaries in the North-Western region of Ukraine. Sick bees’ families had similar clinical signs – the abdomen in sick bees was thickened, filled with fecal matter, the bees moved slowly, noted damage to the pupae among the sealed brood in the spring and summer, and the families took off in August-September. A solution of copper and silver citrate was used in the native state and in such concentrations – 1:2, 1:5, 1:10, diluted in sterile 0.9 % NaCl. The studies were conducted by the disk-diffuse method. The most active influence of a copper and silver citrate solution sample was recorded with native use on both studied cultures, and the enlightenment zone in the mixed culture was significantly greater (by 28.8 %) than in the pure culture of the species Klebsiella pneumoniae. A significant difference was noted between the two cultures of microorganisms (pure and mixed) with similar dilutions (1:2 and 1:10). Due to the presence of genes encoding adhesins, they determine the formation of a biofilm on the surface of the medium during cultivation of the studied microorganisms, we have a pronounced bacteriostatic effect of the native sample. Such changes are explained by the antimicrobial action of AgNPs associated with the mechanisms of AgNPs adhesion to the surface of the cell wall and membrane, penetration of AgNPs into the cell and damage to intracellular structures (mitochondria, vacuole, ribosomes) and biomolecules (proteins, lipids and DNA), induction of cellular toxicity and oxidative stress AgNPs caused by the generation of reactive oxygen species (ROS) and free radicals and modulation of the signal transduction pathways, which is part of the experimental sample. Silver nanoparticles, unlike copper, can be easily synthesized using physical, chemical, electrochemical and biological methods. Therefore, there is a growing demand for the development of effective and environmentally friendly disinfectants in beekeeping. Further research will be aimed at evaluation a toxic dose of LD50 AgNPs in bee gardens, followed by studying the effect of certain doses in hives in vivo, probably not only as an organic disinfectant, but also as an immunomodulator that stimulates the bee’s body, helps to suppress the development of pathogenic microorganisms in the hive.