Acta Microbiologica Bulgarica最新文献

The immunomodulating effect on mice of three products glucomacropeptides obtained from whey with different carbohydrate and peptide components has been studied. After the preliminary application of the preparations at several doses the protective effect in infections with Salmonella typhimurium and Klebsiella pneumoniae increases to different extent. At lower doses fraction 3 increases in vitro the mitogen-induced proliferation of the thymus cells. The phagocytosis of the polymorphonuclear cells on the 24th hour after application of the three preparations is activated. The influence of the structurally different fractions on the immunoprotective effect is discussed.

Comparative analyses have been carried out on the dynamics of invasion of cell cultures from epithelioid (MK and HE-p-2) and fibroblast (mice fibroblasts) types with strain Escherichia coli 0 18 isolated and characterized earlier, as well as on the invasion of the viscera of inbred mice (BDF1) after subcutaneous (foot pad lesion test) and intravenous inoculation with the same strain. It was established that the realization of the invasion potential of E. coli 018 depends on the cell culture used: cell cultures of epithelioid type are much more sensitive. The development of the infectious process and the changes in the number of bacteria in the viscera of the inoculated mice for both ways of introduction of the agent were of the same type. The infectious process after subcutaneous inoculation was accompanied with serious orchitis and progressive inflammatory necrotic changes in the inoculated paws leading to demarcation of the whole limb.

A study was made of the effects of high temperatures and glutaraldehyde on the spores and vegetative cells of Str. thermovulgaris strain 127. It was determined at what treatment times for different temperatures and glutaraldehyde concentrations the spore germination and vegetative cell growth stopped. A high heat stability was found for glucose isomerase, the loss in enzymatic activity increasing with the increase in glutaraldehyde concentration and exposure time. It was determined at what optimum parameters of the combined treatment the growth of the strain stopped and a comparatively high level of glucose isomerase activity was preserved.

Dissociation is a phenomenon when from an initial bacterial population different forms in morphological, physiological aspects have been produced. For bacterial producers of biologically active substances the investigation of this process is important for industrial microbiology. Bacillus subtilis 76 is a producer of proteolytic enzyme complex with milk-coagulating effect. It dissociates in several different forms. Some of them (M, R, S) have been studied. They are plasmidless, prototrophs and tiostrepton-resistant. The results obtained are of a great importance for the future genetic experiments.

The ultrastructure of Pseudomonas pseudomallei, Pseudomonas aeruginosa. Yersinia pseudotuberculosis, Salmonella typhimurium, Listeria monocytogenes was studied after treatment with EDTA. The study established that the most sensitive species were: Pseudomonas pseudomallei and Pseudomonas aeruginosa. In the case of Listeria monocytogenes changes were not observed. Typical ultrastructural changes in the cell wall and the cytoplasmic membrane were established by means of ultrathin sections, as well as with scanning electron microscopy of Pseudomonas pseudomallei and Pseudomonas aeruginosa.

The stimulating properties of three fractions of a glucomacropeptide consisting of different carbohydrate and peptide components were studied. The phagocytic activity of polymorphonuclears was increased on the 24th hour and of macrophages on the 3rd day after application of the preparations to mice. In vitro fraction 3 stimulates the lysozyme activity and the synthesis of proteins and Clq of the macrophages complement. These properties of the cells are collaborated by the established ultrastructural changes. The different composition of the fractions determines their immunostimulating effect.

Electrofusion between cells of yeast strains with different genetic markers are investigated. The yield of fusion products depends strongly on the field conditions and the different compounds in the fusion media.

The kinetics of growth in vitro of strains Yersinia enterocolitica, serovars 0:3, 0:5, 0:8 and 0:9, on culture media containing rhamnose, raffinose and sodium succinate and at different temperatures of cultivation (4 degrees, 25 degrees and 37 degrees C) was characterized. It was established, that all the Yersinia enterocolitica serovars tested, cultivated at 25 degrees C, had the highest growth rate. A significant activation of growth at this temperature was observed when L-rhamnose and especially sodium succinate were used as substrates. The cultivation at 37 degrees C caused a sharp increase in the growth rate which, however, decreased at the end of the experiment (96th hour of cultivation), and certain stimulation of growth was observed on D-raffinose-containing medium. The growth of cells cultivated at 4 degrees C using L-rhamnose as substrate started after a lag-phase of 24 hours, which was better expressed for serovars 0:8 and 0:9. The results reported could be applied to experiments, using methods of isolation of Yersinia enterocolitica from different sources after cultivation at 4 degrees C on L-rhamnose-containing media.

The reproductive potentials of strains Yersinia pseudotuberculosis serovars I, II, III, IV and V cultivated at different temperatures on media containing rhamnose, raffinose and sodium succinate were examined comparatively. It was established that the growth of serovars I, II and III was activated by sodium succinate at temperatures 4 degrees and 25 degrees C, while serovars IV and V showed lower growth rate regardless of the substrate used. At 37 degrees C D-raffinose activated the growth of the cells of serovars IV and V. The studies on the effect of different substrates on the growth of Yersinia pseudotuberculosis in a wide temperature range acquire great importance for the investigating of the process of infection, revealing some aspects of the microorganism-macroorganism relationship.

It was established that cytoplasmic membranes from the stable L-forms of E. coli WF+ induced a 4-5 fold increase of the number of peritoneal exudative cells in mice after single i.p. inoculation. The animals treated with membranes reacted with 4-5 fold higher number of these cells after an i.p. infection by parent form cells or L-form cells, as compared with the reaction of infected, nontreated by membranes mice. The macrophage bactericidal activity was 6-10 fold increased. Using electron microscopy, it was established that the phagosomes containing membranes and their remnants were localized in the peripheral part of the cytoplasm or near the nucleus, without neighbouring lysosomes during the 24-hour interaction. Single cases of phagolysosome fusion were observed.