Taxonomic Specificity of the Sensitivity to the Wickerhamomyces bovis Fungistatic Mycocin.

Wickerhamomyces bovis type strain was found to secret a mycocin with a fungistatic effect at pH from 3.5 to 6.0. The peak of its activity occurred at pH 5.0 in the presence of 3% NaCl. Yeast species sensitive to this mycocin belonged to phylogenetically related genera Ambrosiozyma, Nakazawaea, Ogataea, and Pet- erozyma within the family Wickerhamomycetaceae.

[Intraspecific and Intrageneric Antagonistic Activity of Wickerhamomyces anomalus].

A total of 53 Wickerhamomyces anomalus strains were examined for antagonistic activity, including the nomenclature types of the species with the names presently considered synonymous. Over 70% of the strains exhibited antibiotic activity. According to the action spectra of intraspecific activity, the strains fell into three groups, while according to their activity against other Wickerhamomyces species and phylogenetically related Candida species they formed five subgroups. Antibiotic agents (mostly mycocins) varied in their physicochemical properties.

[Antifungal Activity of Wickerhamomyces silvicola].

Wickerhamomyces silvicola strain Y-178 was shown to secrete a mycocin with a fungicidal effect. It exhibits the highest activity at pH 4.5 and elevated ambient osmotic pressure. Over 140 species belonging to 45 genera of ascomycetous yeasts were sensitive to the mycocin, while basidiomycetous species were resistant. Taxonomically homogenous species usually exhibit a homogenous response to mycocins.

Characterization of two different toxins of Wickerhamomyces anomalus (Pichia anomala) VKM Y-159.

Wickerhamomyces anomalus VKM Y-159 strain produces two types of toxin designated as WAKT a and WAKT b, encoded by chromosomal genes. The WAKT a toxin is heat-labile, pronase sensitive acting in pH range 3-4 affecting on several yeasts including pathogenic Candida species while the WAKT b toxin is protease- and thermo-resistant, acting in pH range 3-7 on two species, Candida alai and Candida norvegica. The rapid decrease of the number of viable cells after toxin treatment demonstrates that both toxins have cytocidic effect.

Production of antifungal cellobiose lipids by Trichosporon porosum.

The yeast Trichosporon porosum suppresses growth of ascomycetes and basidiomycetes belonging to 52 genera. It is due to secretion of a thermostable fungicidal agent. The suppression was maximal at pH 3.5-4.0. Fungicidal preparation obtained from the culture broth was shown to be a mixture of cellobiosides of dihydrodecane acid with different degree of acetylation of cellobiose residue. The preparation caused the death of Candida albicans and Filobasidiella neoformans cells in the concentrations of 0.2 and 0.03 mM, respectively.

Green and brown colour effects in tremellaceous yeast fungi on Staib agar.

Fifty-eight species of basidiomycetous yeast fungi were examined for green and brown colour effects (GCE, BCE) on Staib agar (Guizotia abyssinica creatinine agar). In addition to 9% of Cryptococcus laurentii strains tested, only Cryptococcus podzolicus was GCE-positive. Out of 14 strains of this species, 13 showed a GCE and four showed a BCE. All GCE-positive strains utilized creatinine and creatine as a source of nitrogen but not of carbon. None of these strains could grow at 37 degrees C. Unlike Cr. laurentii, no strains of Cr. podzolicus assimilated glycine as a source of carbon. No association was found to exist between GCE and killer activity. Some tremellaceous creatinine-negative species (Cryptococcus gastricus) showed a BCE whereas some sporidiobolaceous creatinine-positive yeasts (Leucosporidium, Rhodotorula) produced neither GCE nor BCE.

Mastigobasidium, a new teleomorphic genus for the perfect state of ballistosporous yeast Bensingtonia intermedia.

A new genus, Mastigobasidium, is proposed for teliospore-forming, xylose-lacking, ballistosporogenous, glucuronate-positive yeasts. The distinguishing features of the genus are: germination of the teliospore by several long aseptate hyphae; curved phragmometabasidia development on the apices of these hyphae; and production of basidiospores on a peg in clusters. The type strain of heterothallic, nitrate-negative species Mastigobasidium intermedium is VKM Y-2720T (Bullera intermedia type strain) and the allotype strain is VKM Y-2727AL (Sporobolomyces weijmanii type strain).

Effects of Cryptococcus humicola killer toxin upon Cryptococcus terreus envelope: combined fluorometric and microscopic studies.

Killer toxin (microcin) produced by Cryptococcus humicola 9-6 induced interaction of the fluorogenic dyes, ethidium bromide, propidium iodide, and hemimagnesium 8-anilino-1-naphtalenesulfonate, with the sensitive strain of Cryptococcus terreus VKM Y-2253. The toxin also made the cells susceptible to cetyltrimethylammonium bromide and leaky for K+. When excited at 360 nm, cell-bound ethidium (propidium) fluorescence was enhanced by 8-anilino-1-naphtalensulfonate, and cell-bound 8-anilino-1-naphtalensulfonate fluorescence was quenched by ethidium (propidium), indicating energy transfer from 8-anilino-1-naphtalensulfonate to ethidium (propidium). These results suggest that at least a portion of the probe molecules had the same binding site, possibly the cytoplasmic membrane. The parameters of kinetics of microcin action were evaluated fluorometrically. They were found to be identical for all probes and depended on microcin concentration. The fluorescence increment of ethidium and 8-anilino-1-naphtalensulfonate upon binding to microcin-treated cells correlated with the fraction of stainable cells and viability.

Perfect state of Rhodomyces dendrorhous (Phaffia rhodozyma).

After mother-daughter cell conjugation, formation of long holobasidia with terminal basidiospores was observed without mycelium production in Rhodomyces dendrorhous (including the type strain of Phaffia rhodozyma) on polyol-containing media. Basidiospores are not forcibly discharged and germinate by budding. A new genus Xanthophyllomyces (Filobasidiaceae, Tremellales) with a species, X. dendrorhous, is proposed for the teleomorphic state of R. dendrorhous.

Extracellular glycoprotein specific for Saccharomyces sensu stricto.

Using affinity-purified rabbit polyclonal antibodies against an extracellular mannoprotein (gp400) of Saccharomyces cerevisiae, the presence of immunohomologic proteins with similar electrophoretic mobility was shown in the culture medium of S. bayanus, S. paradoxus and S. pastorianus. Cross-reactive bands with different electrophoretic behaviour were observed for S. dairensis, S. exiguus, S. kluyveri, S. unisporus and also for the species moved from Saccharomyces to Arxiozyma, Kluyveromyces, Pachytichospora, Torulaspora and Zygosaccharomyces, in contrast to ascosporous yeasts of other genera in which these proteins were not found.

Species delineation in the genus Nadsonia Sydow.

The genus Nadsonia Sydow is revised on the basis of morphology, physiology, amino acid and fatty acid composition, electrophoretic patterns of some enzymes and DNA relatedness. Two species, N. commutata (type CBS 6640) and N. fulvescens, with two varieties, N. fulvescens var. fulvescens (type CBS 2596) and N. fulvescens var. elongata (type CBS 2594) nov. comb. are recognized. A modified diagnosis of the genus and a key are given.

Metschnikowia lunata sp. nov.

Ascosporulation in the yeast strain designated as Selenotila intestinalis Krassilnikov was achieved. On the basis of mode of ascus formation and ascospore morphology it is included in the genus Metschnikowia Kamienski as a new species, M. lunata.