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N S Egorov

Publications and source records attributed to N S Egorov.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1989

[The role of bitoxibacillin components in the manifestation of its biological activity].

New methods were developed and applied to quantitative determination of beta-exotoxin and antibiotic activity of delta-endotoxin with respect to Micrococcus spp. in bitoxibacillin (BTB) and the fermentation broths prepared under industrial conditions. The biosynthesis of beta-exotoxin in the period of its maximum accumulation during the fermentation was estimated. It was shown that the primary biological effect of BTB on insects consisted in the actions of beta-exotoxin and delta-endotoxin. Biological activity of each of the entomocidal components of the entomocidal components of BTB did not practically correlated with the number of viable spores. There was a correlation between the antibiotic activity of crystalline B. thuringiensis subsp. thuringiensis solutions and the insecticidal activity of the entomopathogenic preparations. Determination of beta-exotoxin and antibiotic activity of delta-endotoxin might be used as a complex procedure for testing the quality of BTB. The method for estimating antibiotic activity of the crystal solutions allowed one to assay the biological activity of other preparations based on Bacillus thuringiensis non-synthesizing beta-exotoxin.

Animals↗
PubMed1989

[Isolation and properties of macrotetrolide synthase from the mycelium of Actinomycetes].

The formation of cyclic polyester antibiotics (macrotetrolides) from nactinic acids in a cell-free system in the presence of a mycelium homogenate of Streptomyces chryzomallus var. macrotetrolidi, a producer of a complex of homologous macrotetrolide antibiotics, was demonstrated. An enzyme catalyzing the formation of an ester macrotetrolide ring and possessing a specific activity of 360 mumol/min/mg of protein has been isolated for the first time from the mycelium homogenate and purified 176-fold with a 18% yield. Macrotetrolide synthase represents a macromolecular complex with a molecular mass of 360 kDa formed by several heterogeneous polypeptides. The effects of physico-chemical environmental factors on the stability and activity of the enzyme were demonstrated. The optimal conditions for the manifestation of the synthase activity (10 mM Tris-HCl, pH 8.0, 10% ethanol, 2% glycerol, 200 micrograms/ml of nactinic acids) were selected. The kinetic parameters of the enzyme-catalyzed macrotetrolide synthesis reaction (Km = 2.9.10(-4) M, V = 22.3 microM/min) were determined.

Anti-Bacterial Agents↗
PubMed1989

[Composition and immunological activity of membrane-bound surface glycoprotein from Crithidia oncopelti].

A membrane-bound glycoprotein with a molecular weight of 10000-12000 was isolated from Crithidia oncopelti and purified. The glycoprotein contained peptide, carbohydrate and lipid fragments and phosphorus. The peptide fragment was represented by 10 amino acids. The carbohydrate fragment was represented by 7 monosaccharides. The lipid part was mainly represented by stearic acid. The glycoprotein showed immunostimulating properties. It had a comitogenic effect on murine spleen cells in vitro and induced tumoricidal activity in murine peritoneal macrophages in vitro and in vivo.

Adjuvants, Immunologic↗
PubMed1989

[Production of antibiotic substances by natural variants of the marine bacterium Vibrio Fischeri].

It was shown that under definite conditions there was competition between natural variants of sea bacteria belonging to V. fischeri. Natural variants of V. fischeri, strain 6 differed in their resistance to streptomycin and had different growth rates under conditions of limited aeration. Morphologically all the variants were identical. V. fischeri P-0, V. fischeri P-1 and V. fischeri P-2 were studied. The study revealed that V. fischeri P-0 produced a non-dialysing thermostable trypsin-sensitive substance inhibiting the growth of V. fischeri P-1 and V. fischeri P-2. The maximum activity of the antibacterial substance was observed when V. fischeri P-0 was grown in a liquid medium with peptone and yeast extract without agitation at 26 degrees C. The inhibiting substance was also active against V. fischeri BKM B995 and V. fischeri P-7 isolated as a result of V. fischeri P-0 exposure to ethidium bromide. The substance had no effect on the following bacterial species: Aeromonas liquefaciens 301, Achromobacter liquefaciens, Pseudomonas putida 15, Pseudomonas fluorescence 7, Escherichia coli AH-32 and Staphylococcus aureus.

Anti-Bacterial Agents↗
PubMed1988

[Use of the method of protoplast fusion in the selection of a nisin producer].

Experimental data on selection of Streptococcus lactis producing the polypeptide antibiotic nisin with the method of protoplast fusing, one of the modern methods of cell engineering are presented. Four strains of Streptococcus lactis differing in their nisin-producing levels and difficult for protoplasting were used in the study. It was shown possible to transfer them to the protoplast form when respective conditions for their preliminary cultivation and regeneration are provided. Distinctive features of these strains with respect to the antibiotic resistance, sugar fermentation and growth component requirements were revealed. The protoplast fusing yielded hybrids differing from the parent strains by a number of phenotypical features and nisin-synthesizing activity.

Genetic Engineering↗
PubMed1987

[Nisin sorption and desorption on different silica adsorbents].

Nisin sorption on some silica adsorbents in columns was studied. Silica gels, silochromes and sintered glass with various pore diameters, various specific surfaces, etc. were tested. Correlation between the adsorbent adsorption capacity with respect to nisin and the adsorbent pore diameter was observed. The tested silochromes, silica gels with the pore diameters of 70-80 nm and sintered glass with the pore diameters of 65-112 nm had the highest adsorption capacity with respect to nisin.

Adsorption↗
PubMed1987

[IR spectrophotometric study of a mixed culture of Streptococcus lactis, strain MSU, and Rhodotorula colostri with agitation of the medium].

Physiological aspects of Streptococcus lactis, strain MSU development in mixed culture with Rhodotorula colostri were studied in connection with nisin biosynthesis. By the IR spectra the average content of the main components in the monoculture cells of S. lactis and its association with the yeast in the stationary growth phase was the following by dry weight: 54-58 per cent of protein, 14-16 per cent of nucleic acids, 26-28 per cent of carbohydrates and 3-5 per cent of lipids. Glucose and nitrogen in the fermentation broth were consumed completely. A significant quantity of KH2PO4 remained in the fermentation broth. Lactic acid excretion was observed. S. lactis, strain MSU was the leading component of the association under the studied cultivation conditions because just its IR spectra dominated in the spectra of the mixed culture.

Lactococcus lactis↗
PubMed1987

[Comparison of the sensitivity of Rhodococcus rubropertinctus R, S and M variants to antibiotic action].

Comparison of sensitivity of 63 clones of R, S and M variants of Rhodococcus rubropertinctus 104 to 6 antibiotics showed that sensitivity of the variants was similar only to erythromycin. Their sensitivity to penicillin, streptomycin, chlortetracycline, rifampicin and actinomycin C was different. Still, they preserved similar regularity: M cells were the most sensitive and R cells were the most resistant. There was a 1.5-3 fold difference in sensitivity of R and M variants to the antibiotics. The number and rate of chlortetracycline absorption by R cells were lower than those of S and especially M cells which must condition their higher resistance to the antibiotic.

Anti-Bacterial Agents↗
PubMed1987

[Intracellular ATP content and nonactin biosynthesis].

The effect of potassium orthophosphate on growth of the mycelium, its ATP contents and biosynthesis of the macrotetrolide antibiotic nonactin by Str. chrysomallus var. macrotetrolidi was studied. Direct dependence of the ATP contents in the mycelium on the amount of the phosphate added to the medium and consumed by the developing actinomycete was shown. Changes in the intracellular content of ATP depended also on the mycelium age. It was characterized by two peaks. Hemin was detected in the actinomycete mycelium. Its levels were sufficiently high and depended on the mycelium age and cultivation conditions, in particular on the phosphate content in the medium. Higher levels of nonactin biosynthesis were characteristic of the mycelium with lower contents of ATP, proteins and hemin. Intensive production of the antibiotic proceeded at the background of decreasing levels of ATP in the mycelium.

Adenosine Triphosphate↗
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↗
PubMed1986

[Role of temperate phage in bacterial dissociation].

The analysis of literary and own data testifies that the dissociants may appear in bacteria population from spontaneous mutations and transfer of genetic material (conjugation, transformation, transduction). The phage conversion and different DNA reorganizations within a cell where prophage plays an active role, probably introduce the largest contribution into the dissociative transitions of variants which occur with high frequency (about 10(-2)-10(-4). The dissociation of various bacteria has been studied with different degree. The role of temperate phage has been shown in splitting of bacteria into variants in the genera Mycobacterium, Corynebacterium, some Bacillus, Clostridium, Staphylococcus, some enterobacteria, Yersinia, Vibrio Pseudomonas, Rhizobium, Nostoc; the participation of prophage in dissociation of bacteria of the genera Xanthomonas, Erwinia, Bacteroides is proposed. A method for obtaining the nondissociating S-variants for stability of biologically active substances synthesized by cells has been suggested.

Bacteria↗