[Antistress cross-protection of UV irradiated yeast cells with participation of extracellular peptide factors].

Antistress effect of extracellular peptides on UV irradiated yeast of different phylogenetic groups was studied. Yeast from different ecotopes and taxonomic groups exposed to UV radiation of a lethal intensity showed a protective effect and reactivating effect with participation of extracellular peptides. The highest protective activity was found in peptide reactivation factors (RFs) of bakery yeast-Saccharomyces cerevisiae, Kluyveromyces fragilis, and Candida utilis; the highest reactivating activity was exhibited by factors of the above-mentioned cultures and Debariomyces hansenii. Cross-protective and reactivating effects of RFs of yeast belonging to different taxonomic groups were demonstrated. Cross-protection increased two to three times after preexposure of reactivation factors to UV light (activation) in contrast to their reactivating effect.

[Pigmented basidiomycete yeasts are a promising source of carotenoids and ubiquinone Q10].

Strains of basidiomycete yeasts isolated from different sources were studied in order to determine the content of carotenoid pigments and ubiquinone Q10 for subsequent selection work to obtain producers of these substances. High specific productivity of carotenoids (600-700 mg/g) was revealed in the representatives of the following species: Cystofilobasidium capitatum. Rhodosporidium diobovatum, R. sphaerocarpum. Rhodotorula glutinis, Rh. minuta, and Sporobolomyces roseus. The ratio of the major pigments (torulene, torularhodine, and beta-carotene) in the representatives of different species was studied. Certain specific features of pigment formation in relation to the taxonomic position of the yeasts were determined. Eurybiont species with substantial ecological lability are the most active producers of carotenoids and ubiquinone Q10 among the epiphytes. It is the first time a comparative analysis of the coenzyme Q10 content in different taxa has been performed using several strains of the same species. The maximal coenzyme Q10 production (1.84 mg/g of dry biomass) was found in the yeast species R. sphaerocarpum.

[Use of sensitivity to antibiotics produced by representatives of the genera Williopsis and Zygowilliopsis in the identification of yeasts]. / Ispol'zovanie chuvstvitel'nosti k antibiotikam, obrazuemym predstaviteliami rodov Williopsis i Zygowilliopsis, v identifikatsii drozhzhei.

Yeast strains belonging to the genera Candida and Hansenula were shown to differ in their susceptibility to the action of protein antibiotics produced by the yeasts Williopsis and Zygowilliopsis. This finding can be used as an additional criterion for yeast identification.

[Relationship between astaxanthin production and the intensity of anabolic processes in the yeast Phaffia rhodozyma]. / Zavisimost' sinteza aktaksantina u drozhzhei Phaffia rhodozyma ot intensivnosti anabolicheskikh protsessov.

The astaxanthin synthesis in the yeast Phaffia rhodozyma was shown to depend on the rate of growth occurring in the first two days of cultivation. The growth rate of the yeast culture studied was preset by the cultivation conditions, among which the C:N ratio was decisive. The intense anabolic processes coupled with active culture growth during the first 24 h significantly inhibited the synthesis of the key enzymes involved in astaxanthin synthesis, which led to a marked decrease in the carotenoid production. It was demonstrated that for the maximum yield of astaxanthin to be obtained from 11 of nutrient medium, it is necessary to carry out cultivation, beginning with the first day, at a growth rate significantly lower than mu(max). The optimum budding rate of the mutant strain Ph. rhodozyma VKPM Y-2409 consistent with the maximum astaxanthin synthesis was determined. The specific astaxanthin productivity of the strain studied was about 7.0 mg/g of dry biomass at a budding rate of <0.5.