Biomedical subjects

N P Zhuravleva

Publications and source records attributed to N P Zhuravleva.

13 recordsLinked to original sources

PubMed1992

[Spontaneous variability in a population of Candida albicans strains].

The spontaneous variability of the populations of C. albicans strains of different genesis in the morphological properties of their colonies and in the potential of the activity of their extracellular proteolytic and phospholipid enzymes has been studied. The isolated types of colonies, differing in their morphology, have the phenotypic character of variability. Different populations of strains exhibited variability in the activity of enzymes, depending on morphological variants isolated from these populations. Selected morphological variants with high potential of their proteolytic enzymes retained stability in this property for 5 generations and can be used in medical practice for the isolation of C. albicans antigens.

Candida albicans↗

PubMed1989

[Mutagenic effect of mitomycin C on different strains of oleandomycin producer Streptomyces antibioticus].

Mitomycin C, a DNA-tropic antibiotic, was shown to have a lethal effect on spore sprouts of two strains of Streptomyces antibioticus, an organism producing oleandomycin. When the time of exposure to the antibiotic increased there was an almost equal decrease in the survival rate. The mutagen action on the morphological variation and antibiotic production of the two closely related strains were diverse due to their genetic differences. The strain isolated after the culture treatment with a chemical mutagen and subjected to a more prolonged maintaining selection showed lower variation with respect to its colony morphology. The other strain isolated after treatment of the culture with high concentrations of its own antibiotic showed lower variation with respect to its antibiotic production property. The shift in the antibiotic production in the direction of the low active variants was characteristic of the both highly productive strains.

Colony Count, Microbial↗

PubMed1982

[Developmental cycle and the cytomorphological characteristics of the oleandomycin producer Streptomyces antibioticus].

The developmental cycle and cytomorphological features of the industrial strain OL-1 and its variant 0968 of the oleandomycin-producing organism were studied. Variant 0968 was obtained as a result of exposure of the spores of strain OL-1 to UV light. When grown under submerged conditions in flasks with the rich medium, the strains were characterized by a complete developmental cycle consisting of three generations of the hyphae. Every generation had a tendency for formation of submerged spores. The UV-induced variant differed from the industrial strain by higher levels of the antibiotic accumulation which correlated with higher rates of the spore germination. The strains were characterized by polymorphism of the mycelium and formation of submerged spores during their cultivation which is likely to prolong the antibiotic synthesis from 120 to 216 hours from the inoculation moment. The long-term selection of the oleandomycin-producing organism on the rich medium markedly changed the culture genotype and resulted in significant changes in the developmental cycle under submerged cultivation conditions. The data may be used for the microscopic control of the process of oleandomycin production.

Culture Media↗

PubMed1979

[Postradiation effect of caffeine on the producer of mycoheptin, Streptoverticillium mycoheptinicum].

The modifying effect of caffeine on irradiated spores of Streptoverticillium mycoheptinicum, producing mycoheptin was found. Postradiation treatment of the strain O883: spores with caffeine resulted in decreased survival of the spores proportionally to the radiation dose increase and postradiation caffeine treatment. An increase in the frequency of the morphologically changed colonies, as well as the low and highly active variants with respect to mycoheptin production was observed. The effect may be explained by the fact that caffeine possibly inhibited the reparation process in the irradiated spores of the strain tested. The method of postradiation treatment of the spores of the mycoheptin-producing organism with caffeine which provided selection of highly active variants by the antibiotic production with the use of definite doses may be considered promising in selection of actinomycetes.

Antifungal Agents↗

PubMed1975

[Action of hygromycin B on the producers of levorin and mycoheptin].

The effect of hygromycin B on survival and variation of the levorin and mycoheptinproducing organisms, i.e. Act levoris, strains 28 and PR-52/67 and streptoverticcium mycoheptincium, strain 44B/I was studied. When added to the agarized medium, hygromycin B had a lethal effect on the above strains. The lethal effect increased with an increase in the concentration from 2.5 80 Units/ml. High modification variation of the colony morphology was observed on media with hygromycin B. At the same time hygromycin B induced morphological and hygromycin-resistant mutants. The variation of the property of the antibiotic production in the above cultures increased under the effect of hygromycinB. The maximum rate of the plus variants was observed at high lethal effects of hygromycin B, when the survival rate of the spores was 10(-3) and 10(-4). An individual reaction of the cultures to hygromycin B was found. Formation of the mutation of resistance to the specific phage in the genome of strain PR of the levorin-producing organism increased its sensitivity to hygromycin and variation of the colony morphology and the property of the antibiotic production.

Actinomycetales↗

PubMed1975

[Production in an Actinomyces levoris culture under the action of an actinophage specific to it of variants with stable preservation of its resistance to the phage].

Act. levoris 28, an organism producing levorin was treated with an actinophage virulent to it. Variants of the organism were isolated from the secondary growth of the culture. As a result of lysogenization with the above phage the variants acquired stability to it which was preserved during the further generations. In the previous experiments carried out by the authors the variants isolated from the secondary growth of the culture after its exposure to the same phage lost their stability to the phage as a result of loosing the prophage by it during the subsequent passages. The phage stable variants did not differ from the initial culture either in the activity of levorin or the levorin composition. The phages found in the initial culture 28, and the virulent mutant were identical with respect to the particles morphology and antigenic properties which confirmed their relation.

Bacteriophages↗

PubMed1973