PubMed Health⌕ Search

Biomedical subjects

N S Egorov

Publications and source records attributed to N S Egorov.

At least 19 recordsLinked to original sources
PubMed1992

[The effect of physicochemical environmental factors on the growth of gram-positive bacterial dissociants].

The growth of R-, S- and M (g)-dissociants of Streptococcus lactis, Bacillus coagulans, Rhodococcus rubropertinctus under the action of some physico-chemical factors: temperature, pH, ultraviolet (UV) rays, high concentration of NaCl and storage have been compared. R-variants gain selective advantage under the influence of UV-irradiation, high temperature and storage; S-variants--at decreasing of active pH of medium; M (g)-variants--at decreasing of growth temperature, high values of pH, increased NaCl concentration. The dissociation has been concluded to enlarge the limits of the species survival.

Bacillus↗
PubMed1992

[Calcium transport in cells of Streptomyces chrysomallus var. macrotetrolidi-- a producer of macrotetrolide antibiotics].

The dynamics of calcium accumulation by cells in batch cultures and by washed cells was defined with a radiotracer procedure for Streptomyces chrysomallus var. macrotetrolidi producing ionophore macrotetrolide antibiotics. It was shown that macrotetrolides added to the cultivation medium could regulate intracellular contents of calcium by participating in cation transport. Moreover, possible functioning of a Ca-ATPase system for the calcium active transport in the streptomycete cells was demonstrated.

Anti-Bacterial Agents↗
PubMed1992

[Isolation of nisin from native solution and its purification on cationites].

It was found possible to use organic sorbents and in particular carboxylic cationites for isolation of nisin from the fermentation broth filtrate and its purification. Nisin is known as a polypeptide antibiotic applied as a preservative. The sorbents were shown to have high exchange capacities by the isolated substance and mechanical strength and resistance. They also proved to be highly stable.

Adsorption↗
PubMed1991

[The separation of true coagulases from other enzymes of the extracellular proteolytic complex of Aspergillus ochraceus by using affinity chromatography].

A complex of proteases has been isolated from the cultural broth of fungi Aspergillus ochraceus HP-19 by precipitation ammonium sulfate. Using the method of affinity chromatography on the biospecific sorbents the conditions for separation of proteases into ones with coagulase activity and with fibrinolytic activity have been found.

Aspergillus ochraceus↗
PubMed1991

[Antibiotic activity of marine gram-negative bacteria].

An antimicrobial substance was isolated from the culture fluid of Vibrio fischeri belonging to ++gram-negative sea bacteria. The substance was shown to be highly active against ++gram-positive cocci and less active against some other ++gram-positive bacteria and fungi. The active substance was defined as a low molecular weight compound which appeared to be thermostable and had positive ninhydrin reaction. The antibiotic formed when the culture was grown in the media containing sea water and protein hydrolysates or yeast extract during the exponential phase. The maximum antibiotic activity was observed during the stationary phase of culture development.

Anti-Bacterial Agents↗
PubMed1990

[Study of nisin, a polypeptide antibiotic produced by a culture of Streptococcus lactis, strain MSU].

The drug nisin produced by the lactic acid bacteria S. lactis, strain MSU, was identified and described. After 18-hour cultivation of the strain the fermentation broth was centrifuged. The centrifugate contained at an average 2000 IU/ml of the antibiotic. It was purified on silica gel C-3, the eluate was lyophilized and the dry substance was studied by disk electrophoresis in 20 per cent PAAG in the presence of sodium dodecylsulfate. It was found that S. lactis, strain MSU, produced a polypeptide component of the molecular weight of 7000 D. Its electrophoretic mobility corresponded to that of nisaplin. Therefore, nisin was shown to be identical to nisaplin.

Anti-Bacterial Agents↗
PubMed1990

[Thiol-dependent serine proteinase from Streptomyces thermovulgaris].

The cultural filtrates of S. thermovulgaris contain a proteinase which is active towards the chromogenic subtilisin substrate, Z-Ala-Ala-Leu-pNa, and azocasein. Pure enzyme preparations were obtained by affinity chromatography on bacitracin-Sepharose with subsequent rechromatography on the same adsorbent. The proteinase was completely inactivated by PMSF and DFP, the specific inhibitors for serine proteinase, by thiol reagents (HgCl2, PCMB) and by the protein inhibitor from S. jantinus. The pH activity optimum for the enzyme is 7.8-8.2, temperature optimum is 55 degrees C. The enzyme is stable at pH 6-9, has a pI of 5.0 and a molecular mass of 32 kDa. When tested against the peptide substrate, the enzyme shows a specificity characteristic for subtilisins. The N-terminal sequence of the enzyme, Tyr-Thr-Pro-Asn-Asp-Pro-Tyr-Phe-Ser-Ser-Arg-Gln-Tyr-Gly, shows a 100% homology with that of terminase, a thiol-dependent serine proteinase. On the basis of the above considerations the enzyme may be related to the subfamily of thiol-dependent serine proteinases.

Amino Acid Sequence↗
PubMed1986

[Effect of the cultivation temperature on gramicidin S biosynthesis under conditions of producer growth limitation by oxygen].

The gramicidin S-producing organisms Bacillus brevis was grown under submerged conditions in fermenters at a temperature of 32 degrees C which is the lower limit of the temperature ranges providing the culture growth. The culture was also grown under the optimal temperature conditions, i.e. 40 degrees C. At the lower temperature the biomass synthesis at the early stage of the culture development was decreased, the intensity of the cell respiration was low and solubility of oxygen in the liquid was increased. Under such conditions the decrease in the levels of dissolved oxygen in the medium was less pronounced than that under the control conditions. At the lower temperature limitation of the culture growth by the deficit of dissolved oxygen lowered and the period of the antibiotic synthesis increased which brought about a rise of the gramicidin S yield by 30-40 per cent.

Bacillus↗
PubMed1979

[Role of gramicidin S in the sporulation of the R+ and R- variants of Bacillus brevis var. G.-B].

The effect of gramicidin S added to the cultivation medium on sporulation of the gramicidin S-producing P+ variant and gramicidin S-nonproducing P- variant of Bacillus brevis var. G.-B. was studied. Gramicidin S added to the synthetic medium with glucose in an amount of 30 and 100 microgram/ml 4 and 7 hours after inoculation with the vegetative cells of R- variant had no effect on the growth of the culture but retarded its sporulation. When gramicidin S was added in an amount of 100 microgram/ml 4 hours after inoculation, the sporulation rate of R- variant strongly decreased, rohile sporulation was not suppressed as it was noted before with respect to R+ variant. Active stimulation of Bacillus brevis var. G.-B. sporulation was observed after addition of gramicidin S 13 hours after development of R+ and R- variants without the antibiotic biosynthesis. Synthesis of gramicidin S by R+ strain was suppressed by the specific inhibitor beta-phenyl-beta-alanine. The amount of gramicidin S added to the medium during the sporulation process of R+ and R- variants decreased. On addition of 30 microgram/ml of the antibiotic it was practically not detectable when the culture showed the greatest number of the spores. Therefore, gramicidin S added to the medium is probably adsorbed by the cells of Bac. brevis var. G.-B. and affects sporulation of R- and R+ variants thus accelerating or retarding this process depending on the cultivation conditions.

Bacillus↗
PubMed1978

[Polymyxin B biosynthesis and tricarboxylic acid cycle enzymatic activity].

Activity of pyruvate dehydrogenase (PDG), isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase and malate dehydrogenase was found in the extracts of the cells of Bac. polymyxa 153, an organism producing polymyxin B. Dependence of the activity of the above enzymes on the carbon source in the medium, aeration conditions, strain features and culture age was shown. A low level of polymyxin B biosynthesis was observed at high activity of PDG and dehydrogenases of the tricarbonic acid cycle. Increased antibiotic production was recorded against the background of decreases values of the above enzyme activities.

Bacillus↗
PubMed1978

[Nisin formation by immobilized cells of the lactic acid bacterium, Streptococcus lactis].

The problem of microbial cell immobilization at present attracts the ever increasing attention of the scientists, since such organisms may be the source of various enzymes. Production of nizin by the immobilized cells of Str. lactis was studied. It was found that the cells of Str. lactis incorporated into polyacrylamide gel produced nizit on definite media. Still, the amount of the antibiotic was 2-3 times lower than in case of using free cells. The effect of a number of factors on the process of immobilization was studied and the influence of some factors, such as temperature, pH, aeration on nizin synthesis by the immobilized cells of the streptococcus was elucidated. Optimal conditions for nizin biosynthesis by the immobilized cells of Str. lactis were developed.

Acrylamides↗
PubMed1977

[Processes of spore formation and gramicidin C formation by Bacillus brevis var. G.B].

Correlation between gramidicin C biosynthesis and sporulation in the process of Bac. brevis var. G.B. cultivation under various aeration conditions was studied. It was shown that biosynthesis of gramicidin C was characteristic of the young cells and its level was the highest during the culture active growth. The time of the sporulating forms appearance depended on the aeration rate which defined the quantitative composition of the population during the phase of the culture active growth and the stationary phase. Under the optimal aeration conditions the spore formation started during the phase of the culture active growth after some decrease in the maximum level of the cell productivity with respect to the antibiotic. When the aeration rate was increased the spore formation was shifted to later periods of the culture development, i.e. the stationary phase and the phase of the cell autolysis, the gap between the highest levels of gramicidin C buosynthesis and the beginning of sporulation being increased. Under certain aeration conditions the spore formation was not observed, while gramicidin C was synthesized. A conclusion has been made that there is no correlation between gramacidine C biosynthesis and sporualtion in Bacillus brevis var. G.B.

Air↗