Acta Microbiologica Bulgarica最新文献

The presence of protein A in the stable L-form of S. aureus BM 3041 was proved. Its amino acid composition and electrophoretic characteristics were compared with the parent strain. The location of protein A on the cytoplasmic membranes of the L-form cells, as well as on the extracellular membranes were established by immunoelectron microscopy. In the cells of the parent bacterium its location on the cell wall was observed.

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.

Comparative studies were carried out of the antiviral efficacy of 11 substances on the replication of Herpes simplex virus type 1 (strain DA), including compounds with selective antiherpes action--bromovinyldeoxyuridine, virazole, phosphonoformic acid, acycloguanosine, citarabine, vidarabine, iododeoxyuridine, and some nonspecific viral inhibitors with antiherpes effect as distamycin A, tunicamycin and deoxyglucose. The antiherpes activity of the substances was tested in two cell systems: cell strain of human embryonic skin-muscle fibroblasts and a cell line of green monkey kidneys. The dose-response curves and the 50% effective dose were defined for each compound by using a microtissue plate test system. Differences in the values of the 50% effective doses of iododeoxyuridine, phosphonoformic acid and distamycin A for the two types of cultures were found out. Bromovinyldeoxyuridine exhibited the highest antiherpes activity in both types of cells, and it was comparatively more active than citarabine, acycloguanosine or iododeoxyuridine, followed by vidarabine and virazole. The results obtained emphasized the necessity of specifying the experimental conditions for comparative studies.

Three auxotrophic mutants and the parent prototroph Streptomyces erythreus BTCC-2 were studied comparatively. The qualitative composition of common lipids was found to be similar in all strains. Changes of phospholipid composition were demonstrated in the mutants.

The dynamics of citric acid biosynthesis and some morphological changes of Asp. niger IM-13 in culture media containing starch hydrolysate and 3% methanol were traced. The culture developed in filamentous form and little fine pellets. Deformed hyphae with characteristic extensions were observed. The changes in Asp. niger IM-13 metabolism were studied by comparing the biomass accumulation, the utilization of reducing substances, the citric acid biosynthesis, pH and the protein content of the control and the experimental variants. A suppression of growth in the period from the 48th hour of cultivation up to the end of the process, suppression of protein synthesis in the micelium and increased synthesis of citric acid were established.

As a result of recombination experiments between auxotrophic mutants of S. erythreus BTCC2 haploid recombinants and heteroclones were isolated. A genetic map of S. erythreus, including 15 auxotrophic loci was constructed by genetic analysis of the segregants of the heteroclones obtained. The genetic distances between 7 key loci on the map were determined and the entire length of the map of about 105 standard recombination units was calculated.