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The objects of research were the bacterial cultures of the genera Salmonella, Escherichia, Pseudomonas, Staphylococcus. The morphology of biofilms and the phases of its development were studied by the method of light and scanning electron microscopy. To study the formation of biofilms in liquid nutrient media, 24-hour microorganism cultures in S-form grown on dense or liquid nutrient media were used. The material was incubated for 24 hours at 37 °C. Then the cover glasses with biofilms formed on them were extracted with tweezers and placed in Petri dishes with filters laid on the bottom (for electron microscopy). In order to preserve the natural architectonics, were fixed by vapor of 25% glutaraldehyde during 3...5 hours. For contrasting preparations, vapor of 2...4% solution of osmic acid were used for 2...3 minutes. The laws of biofilm formation in conditionally pathogenic and pathogenic bacteria were experimentally confirmed: adhesion of single cells, association of exopolysaccharide matrix into clusters, formation of mature biofilm. SEM method shows the possibility of forming a multilayer structure of biofilm, which determines their increased resistance to antimicrobial agents (antibiotics, disinfectants). |
