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Biomedical subjects

V I Golubev

Publications and source records attributed to V I Golubev.

At least 19 recordsLinked to original sources
PubMed1973

On the mechanism of adaptation of micro-organisms to conditions of extreme low humidity.

Low humidity is considered one of the main obstacles for life on Mars. Mechanisms of adaptation to extreme low humidity are investigated in asporogenic yeasts. Cryptococcus albidus var. diffluens inhabits the high mountain deserts of the Pamirs and the Tien Shan. The spin-echo nuclear magnetic resonance method shows that different ways of drying do not extract all liquid water from the cells. Residual humidity of the Cryptococcus cells may reach 30%. The polysaccharide capsule of Cryptococcus delays the drying process noticeably and also collects moisture at low relative humidity. The considerable quantity of conserved liquid water allows Cryptococcus to adapt to the great periodic oscillations of relative humidity resulting from the great diurnal temperature changes in the high mountain deserts. Data obtained indicate the presence of a humidity regulating mechanism on the cellular level in lower plants.

Adaptation, Physiological↗
PubMedDate not supplied

[Glucuronate media for isolating tremelloid yeasts].

D-Glucuronate-containing agar is suggested for evaluation the population density and diversity of tremelloid yeasts in natural cenoses. This medium is superior to the commonly used wort agar on which many representatives of tremelloid yeasts cannot be revealed.

Culture Media↗
PubMedDate not supplied

[Specificity of sensitivity to mycocin from Tilletiopsis flava BKM Y-2838].

The mycocinogenous strain Tilletiopsis flava VKM Y-2823 was found to possess fungicidal activity at pH 3.5-4.5, which was retained after curing the strain by eliminating the extrachromosomal genetic elements. The mycocin produced by the strain had a molecular mass of more than 10 kDa and was readily inactivated by heating and treatment with protease K. This mycocin was found to be active against species of the anamorphic genus Tilletiopsis. The overwhelming majority of other representatives of the order Tilletiales, as well as ascomycetous and basidiomycetous yeasts, which either form or did not from ballistospores of the orders Sporidiales and Tremellales, were resistant to it.

Ascomycota↗
PubMedDate not supplied

[Pseudozyma fusiformata BKM Y-2821--a producer of antifungal glycolipid].

The yeast Pseudozyma fusiformata (the order Ustilaginales) produces an extracellular low-molecular-weight protease-resistant thermostable fungicide, which was active against more than 80% of the 280 yeast and yeastlike species tested. The fungicide, extracted with methanol and purified by column and thin-layer chromatography, was found to consist of glucose and saturated fatty acids.

Antifungal Agents↗
PubMedDate not supplied

[Selenium tolerance of yeasts].

Selenium tolerance of yeasts widely varies: the growth of some yeasts can be inhibited by a selenium concentration as low as 10(-4) M, whereas others can grow in the presence of 10(-1) M selenium. Homogeneous yeast taxa are characterized by a certain level of selenium tolerance, and heterogeneous taxa show a variable level of tolerance to selenium. In general, ascomycetous yeasts are more tolerant to selenium than basidiomycetous yeasts. Among the ascomycetous yeasts, the genera Dekkera and Schizosaccharomyces exhibited the lowest and the species Candida maltosa, Hanseniaspora valbyensis, Kluyveromyces marxianus, and Yarrowia lipolytica the highest tolerance to selenium. Among the basidiomycetous yeasts, the genera Bullera, Cryptococcus, and Holtermannia showed the lowest and the species Cryptococcus curvatus, Cr. humicola, and Trichosporon spp. the highest tolerance to selenium. The selenium tolerance of yeasts depends on the composition of the growth medium, in particular, on the presence of sulfate, sulfur-containing amino acids, and glutamine in the medium.

Adaptation, Physiological↗
PubMedDate not supplied

[A new basidiomycetous yeast species, Cryptococcus mycelialis, related to Holtermannia Saccardo et Traverso].

A new species of the genus Cryptococcus, Cr. mycelialis (the type strain VKM Y-2863), is described based on the taxonomic study of four strains isolated from the soil and plant samples collected on the South Georgia and East Falkland islands. This species differs from the known Cryptococcus species in its ability to form a true monokaryotic mycelium with pseudoclamp connections and haustoria. The species can be distinguished from the phylogenetically related and phenotypically similar species Holtermannia corniformis and Cr. nyarrowii by some assimilatory reactions, maximum growth temperature, and sensitivity to mycocins.

Atlantic Islands↗
PubMedDate not supplied

[Selection and study of potent lactose-fermenting yeasts].

Whey-fermenting Kluyveromyces cultures were revealed among 105 yeast strains assimilating lactose. Eighteen most potent strains isolated from milk products fermented galactose, sucrose, and raffinose, in addition to lactose. Many yeast strains fermented inulin. Most strains were resistant to cycloheximide and grew in medium containing glucose, NaCl, and ethanol at concentrations of up to 50, 11-12, and 10-12%, respectively (4 degrees C). Three strains had mycocinogenic activity. After fermentation of whey with selected yeast strains at 30 degrees C for 2-3 days, ethanol concentration was 4-5%.

Culture Media↗
PubMedDate not supplied

[The fungicidal activity of an extracellular glycolipid from Sympodiomycopsis paphiopedili sugiyama et al].

The yeast Sympodiomycopsis paphiopedili (Ustilaginomycetes) produces an extracellular glycolipid, which possesses the maximum antifungal activity at the pH of the medium equal to 4.0-4.5. Among the approximately 300 tested species of yeastlike and mycelial fungi, more than 80% (including species pathogenic for plants, animals, and humans) were found to be susceptible to this glycolipid.

Antifungal Agents↗
PubMedDate not supplied

[Characterization of Schizosaccharomyces hominis].

The cultural, morphological, physiological and biological characteristics of Schizosaccharomyces hominis, Benedek strain BKM Y-650 were under study. This name is regarded as synonymous to Schizosaccharomyces pombe Lindner.

Animals↗
PubMedDate not supplied

[Capsule formation in saprophytic yeasts].

Among ten carbon sources and five nitrogen sources tested, D-mannose (3%) and peptone (0.2%) were found to be the best ones for stimulating capsule formation by the yeast Cryptococcus magnus. Addition of yeast extract (0.1%) to the medium favoured formation of larger capsules. Elevated concentrations of mannose and peptone inhibited capsule formation. Comparison of the results obtained with the data about the effect of cultivation conditions on capsule formation by the pathogenic yeast revealed no considerable differences between the latter and the saprophytic yeast.

Carbohydrate Metabolism↗