[Molecular Polymorphism of ß-Galactosidase LAC4 Genes in Dairy and Natural Strains of Kluyveromyces Yeasts].

The ability to ferment lactose is a characteristic peculiarity of dairy Kluyveromyces lactis yeasts; the vast majority of other yeast species are not able to assimilate this disaccharide. Molecular polymorphism of LAC4 genes encoding ß-galactosidase controlling lactose fermentation is not well studied, and the published data concern only a single strain (K. lactis var. lactis NRRL Y-1140) isolated from cream in the United States. We studied ß-galactosidase genes in lactose-fermenting К lactis strains isolated from dairy products and natural sources in different regions of the world using molecular karyotyping, Southern hybridization, and sequencing. It was established that the ability to ferment lactose in К. lactis var. lactis dairy yeasts is controlled by at least three polymeric LAC loci with different chromosomal localization: LAC1 (chromosome III), LAC2 (II), and LAC3 (IV). Most of the strains we studied had the LAC2 locus. A comparative analysis of ß-galactosidases of the Kluyveromyces genus yeasts and these enzymes from other yeasts was conducted for the first time. Phylogenetic analysis detected significant differences between the LAC4 proteins of yeasts of the Kluyveromyces genus (K. lactis, К. marxianus, К. aestuarii, К. nonfermentans, К. wickerhamii), Scheffersomyces stipitis, Sugiyamaella lignohabitans, and Debaryomyces hansenii. A correlation between ß-galactosidase sequences and ecological origin (dairy products and natural sources) of Kluyveromyces strains was found. The group of dairy strains is heterogeneous and includes К. lactis var. lactis and К. marxianus yeasts (99.80-100% similarity), which indicates a common origin of their LAC4 genes. Phylogenetic analysis of ß-galactosidases indicates a close genetic relationship of dairy and hospital strains of К. lactis var. lactis and К. marxianus. Clinical isolates are able to ferment lactose and appear to originate from the dairy yeasts.

Genetic relationship and biological status of the industrially important yeast Saccharomyces eubayanus Sampaio et al.

The genomes of the recently discovered yeast Saccharomyces eubayanus and traditional S. cerevisiae are known to be found in the yeast S. pastorianus (syn. S. carlsbergensis), which are essential for brewing. The cryotolerant yeast S. bayanus var. uvarum is of great importance for production of some wines. Based on ascospore viability and meiotic recombination of the control parental markers in hybrids, we have shown that there is no complete interspecies post-zygotic isolation between the yeasts S. eubayanus, S. bayanus var. bayanus and S. bayanus var. uvarum. The genetic data presented indicate that all of the three taxa belong to the same species.

Genetic Polymorphism of Sherry Saccharomyces cerevisiae Yeasts.

The review deals with natural diversity of sherry ("flor") Saccharomyces cerevisiae yeasts. Various properties of these yeasts are analyzed: life cycles, fermentation of sugars, sensitivity to methyl violet and killer toxins, and resistance to ethanol and sulfite. Special attention is paid to molecular identification and differentiation of sherry yeasts. The history of their nomenclature is considered, including the names of possible subpopulations: "aceti," "beticus" ("cheresienses"), "cordubensis," "gaditensis," "hispanica" ("prostoserdovii"), and "oxidans."

[Taxonomic Genetics of Methylotrophic Yeast Genus Komagataella: New Biological Species K. kurtzmanii].

Genetic hybridization analysis revealed that industrially important species Komagataella kurtzmanii has re productive postzygotic isolation from K. pastoris, K. populi, K. phaffii, K. pseudopastoris, and K. ulmi. Therefore, it represents a new biological species of the genus Komagataella. The genetic data are in perfect agree ment with the molecular taxonomy of the genus Komagataella.

New family of pectinase genes PGU1b-PGU3b of the pectinolytic yeast Saccharomyces bayanus var. uvarum.

Using yeast genome databases and literature data, we have conducted a phylogenetic analysis of pectinase PGU genes from Saccharomyces strains assigned to the biological species S. arboricola, S. bayanus (var. uvarum), S. cariocanus, S. cerevisiae, S. kudriavzevii, S. mikatae, S. paradoxus, and hybrid taxon S. pastorianus (syn. S. carlsbergensis). Single PGU genes were observed in all Saccharomyces species, except S. bayanus. The superfamily of divergent PGU genes has been documented in S. bayanus var. uvarum for the first time. Chromosomal localization of new PGU1b, PGU2b, and PGU3b genes in the yeast S. bayanus var. uvarum has been determined by molecular karyotyping and Southern hybridization.

[Identification and polymorphism of pectinase genes PGU in the Saccharomyces bayanus complex].

Pectinase (endo-polygalacturonase) is the key enzyme splitting plant pectin. The corresponding single gene PGU1 is documented for the yeast S. cerevisiae. On the basis of phylogenetic analysis of the PGU nucleotide sequence available in the GenBank, a family of divergent PGU genes is found in the species complex S. bayanus: S. bayanus var. uvarum, S. eubayanus, and hybrid taxon S. pastorianus. The PGU genes have different chromosome localization.

[Correction of Metabolic Processes in Rats during Chronic Endotoxicosis using Isotope (D/H) Exchange Reactions].

The effect of isotope exchange reactions (deuterium/protium, D/H) on morphofunctional indices and the state of the antioxidant blood system in rats was studied under physiological conditions and during experimental chronic endotoxicosis of hepatorenal genesis. It was demonstrated that introduction of water with a decreased content of deuterium in the food rations of rats results in a decrease in its concentration in the blood plasma by 32-36% (to 98-106 ppm) and in lyophilized liver, kidney, and heart tissues by 13-17% (to 123-128 ppm). It was noted that it is accompanied by correction of metabolic processes, an increase in the functional activity of nonspecific protection system, and an increase in the body weight growth by the 42nd day in the group of animals that passed (for 14 days) the stage of preliminary adaptation with a change in the D/H ratio in the organism.

[Invertase Overproduction May Provide for Inulin Fermentation by Selection Strains of Saccharomyces cerevisiae].

In some recent publications, the ability of selection strains of Saccharomyces cerevisiae to ferment inulin was attributed to inulinase activity. The review summarizes the literature data indicating that overproduction of invertase, an enzyme common to S. cerevisiae, may be responsible for this phenomenon.

[Hybrid Sterility of the Yeast Schizosaccharomyces pombe: Genetic Genus and Many Species in statu nascendi?].

A phenomenon of ascospore death was observed in a number of Schizosaccharomyces pombe interstrain hybrids. Meiotic recombination of the control parental auxotrophic markers was, however, observed in a random ascospore analysis. Genetic and molecular biological data indicated existence of at least geographical divergence of the genomes in Sch. pombe populations. Classification of the genus, species, and varieties of these yeasts is discussed.

[Towards Reinstatement of the Yeast Genus Zygowilliopsis Kudriavzev (1960)].

Experimental data on genetic molecular classification and identification of the yeast genus Zygowilliopsis are summarized. The genus is represented by at least five biological species and three varieties: Z. californica: var. californica, var. dimennae, and var. fukushimae. Biogeography, ecology and killer activity of Z. californica yeasts is considered. Heterogeneity of the taxonomic genus Barnettozyma Kurtzman et al. (2008) and the necessity for its revision are discussed.

[Molecular polymorphism of IB-fructosidase SUC genes in the yeast].

SUC gees encoding bea-fructosidase has been investigated in the yeast genus Saccharomyces. We have determined nucleotide sequences of subtelomeric SUC3, SUCS, SUC7, SUC8, SUC9, S UCO10 genes of S. cerevisiae and SUCa gene o:f S. arboricola. Comparisns of nucleotid sequences of all known SUCgenes revealed predominance of transitions C-->T in the third codon position, Which are silent. The amilioacids sequences of p-fructosidases studied have identity of 88-100%.4'Most divergent are SUCa (S.'arboricola) and SUCb (S. bayanus), having amino acid identity.with the other SUCproteins less than 92%. It wasdetermined that accumulation of the polymeric SUC genes takes place in industrial populations of S. cerevisiae, while the other Saccharomyces species (S. arboricola, S.:bayanus, S. cariocanuis, kudriavzevii, S. mikatae and S. paradoxus) each harbor only one SUCgene. Subtelomeric repeats of pructosidase SUCgenes cobetald appear in the genome of S. cerevisiae under the effect of selection in the course of their domestication.

[Finding of dairy yeasts Kluyveromyces lactis var. lactis in natural habitats].

Well-known yeasts Kluyveromyces lactis var. lactis, which are usually associated with dairy prod- ucts, were discovered in nature (in woodland park soil under Impatiens glandulifera Royle plants). Reliable identification of the yeasts was carried out using physiological criteria (lactose and maltose utilization) and molecular markers (nucleotide sequence of the 5.8S-ITS rDNA fragment, pulsed-field electrophoresis, and Southern hybridization of chromosomal DNA with the LAC4 probe). Ecology of KI. lactis var. lactis is discussed.