Mikrobiologiia最新文献

Propionibacterium freudenreichii RVS-4-irf is a probiotic bacterium producing antimicrobialexometabolites applicable for foodstuff protection. Production of antimicrobial factors other than lowmolecularpropionates was observed in media with and without trypton. A method was developed for productionof the fraction of high-molecular mass exopolymers from the culture liquid. Their polypeptide nature wasconfirmed using proteinase K. The preparation of extracellular polypeptides from P. freudenreichii RVS-4-irfexhibited species-specific activity in suppression of fungal and bacterial growth.

Secondary metabolites of 22 fungal strains (genus Aspergillus, section Usti) isolated at diverse geographicregions, including the Arctic permafrost deposits, were studied. The studied strains were found tosynthesize a variety of biologically active compounds, structurally identified as drimane sesqueterpenoids,isoquinoline alkaloids (TMC-120 A−C, derivative 1), meroterpenoids (austalides О and J), and anthraquinonepigments (averufin, versicolorin C). Desferritriacetylfusigen production by A. calidoustus isolates isreported for the first time. The individual spectra of secondary metabolites were used for reidentification of17 strains, of which 15 were identified as A. calidoustus and two, as A. pseudodeflectus.

Ability of actinobacteria Rhodococcus opacus 1CP to survive under unfavorable conditions and retain its biodegradation activity was assessed. The morphological and ultrastructural features of R. opacus 1CP cells degrading benzoate in the presence of oxidants and stress-protecting agents were investigated. The cells of R. opacus 1CP were resistant to oxidative stress caused by up to 100 mM H2O2 or up to 25 μM juglone (5-oxy-1,4-naphthoquinone). After 2 h of stress impact, changes in the fatty acid composition, increased activity of antioxidant enzymes, and changes in cell morphology and ultrastructure were observed. The strain retained its ability to degrade benzoate. Quercetin had a protective effect on benzoate-degrading cells of R. opacus 1CP. The strategy for cells survival under unfavorable conditions was formulated, which includeddecreased cell size/volume and formation of densely-packed cell conglomerates, in which the cells are embedded into a common matrix. Formation of conglomerates may probably be considered as a means for protecting the cells against aggressive environmental factors. The multicellular conglomerate structure and the matrix material impede the penetration of toxic substances into the conglomerates, promoting survival of the cells located inside.

The taxonomic composition of microbial communities of Lake Baikal surface microlayer was studied by pyrosequencing of the 16S rDNA amplicons. Statistically reliable differences were found between bacterioneuston of the shallow and deep-water stations. The shallow station community was characterized by higher diversity than the deep-water one. While bacterioneuston communities were shown to be less diversethan the water column communities, their diversity was comparable to that of other biofilm associations. Microbial communities of Lake Baikal surface microlayer were shown to be similar to those of the water column in the composition of predominant phyla, while differing considerably at the genus level. Bacterioneuston of Lake Baikal was comparable to microbial communities of the surface microlayer of other freshwater basins, although it was characterized by high abundance of the Alphaproteobacteria and Verrucomicrobia. High abundance of photoheterotrophs compared to the water column communities of other freshwater basins was another distinctive feature of Lake Baikal bacterioneuston. Our results showed the Lake Baikal surface microlayer to be a specific microbial community with low species diversity and relatively high abundance of photoheterotrophic microorganisms.

The review deals with natural diversity of sherry (“flor”) Saccharomyces cerevisiae yeasts. Variousproperties of these yeasts are analyzed: life cycles, fermentation of sugars, sensitivity to methyl violet and killertoxins, and resistance to ethanol and sulfite. Special attention is paid to molecular identification and differentiationof sherry yeasts. The history of their nomenclature is considered, including the names of possiblesubpopulations: “aceti,” “beticus” (“cheresienses”), “cordubensis,” “gaditensis,” “hispanica” (“prostoserdovii”),and “oxidans.”

Effect of chromate ions on the culture of a marine diatom Phaeodactylum tricornutum was studied using an M-PEA-2 fluorimeter, which carries out simultaneous measurement of fluorescence induction and redox transformations of the P700 pigment within a millisecond range. Chromate ions were shown to inhibit electron transport in PS II and decrease the rate of QА reduction. This results in decreased values of the quantum yield of electron transport in PS II (ϕEo) and performance index (PI ABS), lower rates of P700 reduction, and increased energy (DI0/RC) and ΔpH-dependent nonphotochemical quenching (q E ). Emergence of the slow component of P700 reduction was observed, indicating the activation of cyclic transport in the presence of chromate. Performance index (PI ABS), which was the most sensitive parameter, may be recommended for detection of chromate ions at early stages of their toxic action. The fluorescence parameter F O is promising application in biotesting to assess the algal growth rates.

Diversity of magnetotactic bacteria in the Moskva River at the Strogino area was studied using microscopy and phylogenetic analysis. Magnetotactic cocci were the predominant morphotype. Phylogenetic analysis of the 16S rRNA gene sequences revealed 13 OTUs of the orders Magnetococcales and Rhodospirillales, class Alphaproteobacteria. The shares of the relevant sequences were 90 and 10%, respectively. An axenic culture of magnetotactic spirilla was isolated from the studied community. According to the results of the 16S rRNA gene sequencing, the isolate was identified as a new Magnetospirillum species.

During the summer period (15–25°C), 34 strains of methylotrophic bacteria associated with differentspecies of herbs, shrub, and trees in Pushchino (Moscow oblast, Russia) were isolated on the mediumwith methanol. Predominance of pink-colored Methylobacterium strains in the phyllosphere of many plantswas confirmed by microscopy, enumeration of the colonies from grass leaves, and sequencing of the 16SrRNA genes. Colorless and yellow-pigmented methylotrophs belonged to the genera Methylophilus, Methylobacillus,Hansschlegelia, Methylopila, Xanthobacter, and Paracoccus. All isolates were able to synthesize planthormones auxins from L-tryptophan (5−50 μg/mL) and are probably plant symbionts.

Microbial biofilms are a basic form of existence of bacteria in the environment, as well as in the animal and plant organisms. The patterns of biofilm formation depending on cultivation conditions is presently insufficiently studied. This paper presents experimental results on the effect of carbon sources on biofilm formation and movement on the swarming type in a phytopathogenic bacterium Pectobacterium carotovorum. A polyol inositol was shown to cause a significant activation of these processes.