Mikrobiologiia最新文献

Bacterial mats formed by a colorless sulfur bacterium Thioploca sp. in the area of the Posolski Bank cold methane seep (southern Baikal) were -studied using electron microscopy and phylogenetic analysis. Morphologically the bacteria were identified as Thioploca ingrica.- Confocal microscopy of DAPI-stained samples revealed numerous rod-shaped, filamentous, and spiral microorganisms in the sheaths, as well as in- side and between the trichomes. Transmission electron microscopy revealed nonvacuolated bacteria and small cells-without cell envelopes within the sheath. Bacteria with pronounced intracytoplasmic membranes characteristic; of type I methanotrophs were observed at the outer side of the sheath. Based on analysis of the 16S rRNA gene sequences, the following phyla were idenified in the sheath community: Bacteroidetes, Nitro- spira, Chloroflexi, Planctomycetes, Verrucomicrobia,'y-, and 6-Proteobacteria, Euryarchaeota, Crenarchaeota, and Thaumarchaeota, as well as anammox bacteria. A hypothetical scheme of matter flows in the Lake Baikal bacterial mats was proposed based on the data on metabolism of the cultured homologues.

Phylogeneticanalysis based,on comparison of the 16S rRNA gene sequences in combination with comparative analysis of physiological, biochemical, and chemotaxonomic characteristics and DNA-DNA hybridization revealed that "Methylobacillusfructoseoxidans" 34 (VKM B-1609 = DSM 5897 and-Methylov- orus glucosotrophus 6B 1T (ATCC 49758T = DSM 6874T = VKM B- 1745T = NCIMB 13222 ) belong to the same Methylovorus species. Extended description of the limited facultative methylotroph Methylovorus gluco- sotrophus is proposed, which includes the fructose-utilizing strain 34. Emended description of Methylovorus glucosotrophus is provided.

A method is proposed for integral assessment of the propagation of microbial cells and viral parti- cles during seasonal thawing of relic ice wedge layers. The results of on-site and laboratory investigation car- ried out in the upper part of permafrost exposure at Mamontova Gora (Yakutiya, Russia) are presented. To increase reliability of the results, suspensions of two microbial species and two coliphage species were intro- duced as biomarkers directly on the surface of thaing ice and in the meltwater flow. Each of the four different model biological objects was shown to possess unique parameters of movement in the meltwater flow and is able to move 132 m in 25-35 min with the water flow.

High-throughput sequencing was used for comparative analysis of microbial communities of the water and mat from the Hoito-Gol mesothermal mineral sulfide spring (Eastern Sayan Mountains, Buryat Republic). Activity of microbial communities was determined. While both spring biotopes were dominated by members of three bacterial phyla, Proteobacteria, Bacteroidetes, and Firmicutes, they differed drastically in the composition of predominant phylotypes (at the genus level). In the water, the organisms wide spread in aquatic'environments were predominant, mostly aerobic chemoorganotrophs of the generaAcinetobacter, Pe- dobacter, and Flavobacterium. In the microbial mat,;the organisms actively involved in the sulfur cycle predominated, including sulfur-reducing bacteria Sulfurospirillum, sulfate-reducing deltaproteobacteria, sulfur- oxidizing chemoautotrophic bacteria, anoxygenic phototrophic bacteria of,the phyla Chloroflexi and Chloro- bi, as well as purple bacteria belonging to the Q-, P--, and y-Proteobacteria. Microbial mats of the spring exhibited higher phylogenetic diversity compared to high-temperature mats containing photosynthetic microorganisms.

This study assessed the microbial diversity, activity, and composition of methane-oxidizing communities of a subarctic wetland in Russia,with mosaic cover of Sphagnum mosses and lichens of the genera Cladonia and Cetraria. Potential methane-oxidizing activity of peat sampled from lichen-dominated wetland sites was higher than that in the sites dominated by Sphagnum mosses. In peat from lichendominated sites, major bacterial groups identified by high-throughput sequencing of the 16S rRNA genes were the Acidobacteria (35.4-41.2% of total 16S rRNA gene reads), Alphaproteobacteria (19.1-24.2%), Gammaproteobacteria (7.9-11.1%), Actinobacteria (5.5-13.2%), Planctomycetes (7.2-9.5%), and Verrucomicrobia (5.1-9.5%). The distinctive feature of this community was high proportion of Subdivision 2 Acidobacteria, which are not char- acteristic for boreal Sphagnum peat bogs. Methanotrophic community composition was determined by mo- lecular analysis of the pmoA gene encoding particulate methane monooxygenase. Most (-80%) of all pmoA gene fragments revealed in peat from lichen-dominated sites belonged to the phylogenetic lineage represented by a microaerobic spiral-shaped methanotroph, "Candidatus Methylospira mobilis." Members of the genus Methylocystis, which are typical inhabitants of boreal Sphagnum peat bogs, represented only a minor group of indigenous methanotrophs. The specific feature of a methanotrophic community in peat from lichen-dominated sites was the presence of uncultivated USCa (Upland Soil Cluster alpha) methanotrophs, which are typical for acidic upland soils showing atmospheric methane oxidation. The methanotrophic community composition in lichen-dominated sites of a tundra wetland, therefore, was markedly different from that in bo- real Sphagnum peat bogs.

B820 subunits from a purple sulfur bacterium Ectothiorhodospira. haloalkaliphila strain ATCC 51935T were obtained by treatment of Carotenoid free LH I-RC complexes of this bacterium with P--octylglu- copyranoside (β-OG). The same complexes with 100% carotenoid content were unable to dissociate to B820 subunits, but disintegrated to monomeric bacteriochlorophyll (BChl) regardless of their carotenoid compo- sition. The degree of dissociation of the LH 1-RC complexes with an intermediate content of carotenoids (the' B820 formation) was directly dependent on the quantity of carotenoids in the samples. The resulting B820 subunits did not contain carotenoids. B820 subunits easily aggregated to form a complex with an absorption . peak at 880 nm at decreased β-OG concentration. Analysis of the spectra of the LH I-RC complexes isolated from the cells with different'levels of carotenogenesis inhibition led to the conclusion of the heterogeneity of the samples with a predominance in them of (a) the fraction with 100% of carotenoids and (b) the fraction of carotenoid free complexes.

For heterotrophic microorganisms (44 strains) isolated-from the surface film of Lake Baikal, iden- tification was carried out and their. physiological and biochemical characteristics were determined. Com- pared to the water column, diversity of cultured heterotrophs was low, indicating formation of stable micro- bial communities at the air-water interphase interface. Heterotrophic bacteria isolated from the surface mi- crolayer exhibited the enzymatic activity comparable to that for strains form other biofilm associations. Deinococcusfi6us strain NA202 'vas the most active component of the community, capable of utilization of the broadest spectrum of mono- and disaccharides,'sugars, and amino acids. This strain possessed the highest diversity of extracellular enzymes and was the most resistant to UV radiation. The physiological and bio- chemical properties of this strain may-be responsible for its adaptation to survival in extreme conditions of the surface microlayer. Our results improve our understanding of occurrence of UV-resistant strains in freshwater ecosystems.

The community of anoxygenic phototrophic bacteria (APB) in the water column of Lake Kislo- Sladkoe (Kandalaksha Bay, White Sea), which has recently become separated from the sea, was investigated in March-April 2012, March-April 2013, and in September 2013. The lake, which was previously considered meromictic, was in fact mixed and was strongly affected by the sea. In winter the lake is sometimes washed off with seawater, and this together with the seasonal cycles of succession processes determines the succession of the community. The consequences of the mixing in autumn 2011 could be observed in the APB community as late as autumn 2013. Green-colored green sulfur bacteria (GSB) usually predominated in the chemocline. In winter 2013 stagnation resulted in turbidity of water under the ice, which was responsible for both predom- inance of the brown GS B forms and the changes ratio of the species of purple sulfur bacteria (PS B) in anoxic water layers. Production of anoxygenic photosynthesis in the lake was at least 240 mg C m-2 day-- in September and 0-20 mg C m-2 day- in March-April, which corresponded to 40 and 69%, respectively, of oxygenic photosynthesis. Okenone-containing purple sulfur bacteria, strain TcakPS12 were isolated in 2012 from lake water. The ells of this strain form filaments of not separated cells. Strain TcakPS12 exhibited 98% similarity with the type strains of Thiocapsapendens DSM.236 and Thiocapsa bogorovii BBS, as well as with the strains AmPS10 and TcyrPS 10, which were isolated from Lake Kislo-Sladkoe in 2010.

Interactions of the main components of microbial planktonic food web (bacteria, heterotrophic nanoflagellates, and viruses) were studied in a protected overgrown littoral zone of the Rybinsk Reservoir (Upper Volga).. The effect of bird colonial, settlements (the Laridae family) on these processes was deter- mined. The following systems exhibited significant negative correlations: "heterotrophic nanoflagellates- large rod-shaped bacteria" ("predator-prey"), "viruses-bacteriophages-bacterial products" ("parasite-. host") and "heterotrophic nanoflagellates-viruses-bacteriophages." Relations between biotic factors con- trolling bacterial development were more pronounced outside the zone affected by colonial bird settlements. Near the bird colony the role of viruses in mortality of planktonic bacteria increased. Reproduction of bacte- rial cells accelerated in response to the increase in feeding activity of heterotrophic nanoflagellates. Viruses- bacteriophages and heterotrophic nanoflagellates probably eliminate different targets until medium-sized cells become predominant in the bacterial community. Then heterotrophic nanoflagellates consume bacterial cells infected with viruses.