ULTR ASTRUCTUR AL CHANGES OF BACTER IA PASTEUR ELLA MULTOCIDA INFLUENCED BY NITROFUR ANBACTER ICIDAL CONCENTR ATIONS OF THE DRUG
The article presents the results of the study of the effect of the minimum (12.5 µg/l) and four (50 µg/ ml) bactericidal concentrations of nitrofuran on the bacteria Pasteurella multicida B651. Under the influence of the drug at a dose of 12.5 µg/ml for 3 hours, pasteurellas showed a decrease in the clarity of the contours of the cell surface structures and nucleoid differentiation, electron-dense formations in the cytoplasm. By increasing the duration of the effect of the minimum bactericidal concentration of the drug to 6 hours, the outer and inner electron-dense layers of the cell wall of pasteurellas disappeared almost completely. At the poles of many cells as a result of cytoplasmic lysis, electron-transparent zones were observed. At the site of the nucleoid, electron-trans- parent zones were found, in which a network of electron-dense filaments was revealed. The impact of nitrofuran preparation at a dose of 50.0 µg/ml for pasteurellas during 3 hours was accompanied by more pronounced chang- es of the ultrastructure of microbial cells. The space between the outer and periplasmic membranes was revealed in bacteria. The cytoplasm was localized on the periphery of the cells, it lost the granular structure. The nucleoid was not differentiated. When exposed to fourfold bactericidal concentration of nitrofuran for 6 hours, the cell wall of the pasteurellas thinned. At the poles of the cells extensive electron-transparent zones appeared. The remaining part of the cytoplasm acquired a pronounced homogeneous form, became more electron-transparent and ob- tained a non-uniform optical density. A significant part of the cells lysed.