Antimicrobial activity of silver salt and silver nanoparticles in different forms against microorganisms of different taxonomic groups.

The development of antiseptics and medical products (bandaging materials, sponges, etc.) based on silver nanoparticles is an essential task due to the growing resistance of pathogenic microorganisms to medicines long used in clinical practice. Using silver nanoparticles for the same purpose is promising, but the potential hazards and cumulative effects in the application of nanoparticles requires a thorough study of those materials. To evaluate the efficiency of antiseptics and medical products based on silver nanoparticles, it is necessary to conduct an in-depth study of the activity of silver nanoparticles in different forms and immobilized in carriers. The study examines the resistance of bacterial and fungal cultures to silver nanoparticles produced by chemical reduction and microbiological synthesis. The study of resistance was carried out in different growth phases of pathogenic microorganisms and in both liquid and solid media. Chemically and microbiologically synthesized nanoparticles were added in the form of a suspension, as well as encapsulated in chitosan-PVA matrices. It was experimentally discovered that, depending on the medium and form of the silver, the antibacterial effect would significantly differ due to changes in the mechanisms regarding the release of nanoparticles and their activity against the cells of pathogenic and potentially pathogenic microorganisms.

Halobacterium salinarum storage and rehydration after spray drying and optimization of the processes for preservation of carotenoids.

Spray drying is appropriate for the preservation of halophilic microorganisms due to the nature of these microorganisms, as they survive in adverse environmental conditions by being encapsulated in salt crystals. Artificial neural networks were in this study used to optimize practically significant spray-drying regimes of the C50-carotenoids producer Halobacterium salinarum. Immediately after drying, the samples contained up to 54% halobacterial biomass and less than 5% moisture, and the level of preservation of carotenoids was 95-97%. The storage of biomass at 4 °C resulted in the gradual degradation of the carotenoids, which reached 58-64% in the best samples after 1 year. A comprehensive study of changes in halobacteria biomass after spray drying and the nature of the damage provided new data on the survival and preservation of cells and biologically active substances in the various spray-drying regimes and at different storage times.