Diversity and function of microbial communities in sediments from different deep-sea habitats

Deep-sea floors are diverse environments that range from permanently cold (desert-like plains) to hot systems (hydrothermal vents). In hot systems, primary productivity is performed by microbial communities which use chemical energy generated by geological processes (lithotrophy). This energy transfer from mantle to the ocean is as yet poorly understood, and the diversity and activity of microbes at these sites is therefore an interesting target for microbial ecologists. However, the vast majority of all globally distributed deep-sea sediments is permanently cold. The distribution of microorganisms in deep-sea floors and the factors controlling it at small and large scales are important for the understanding of the mechanisms that regulate biodiversity. During this thesis, hydrothermally influenced sediments of the peridotite-hosted Logatchev hydrothermal vent field were investigated in an interdisciplinary study to reveal the diversity and activity of the associated microbial communities. In situ microprofiles showed that these sediments were controlled by diffusive transport, instead of previously reported advective processes. White mats on top of these sediments resemble Beggiatoa-mats from the basalt- hosted field in the Guaymas Basin. However, fluorescence in situ hybridization revealed that the overlying sulfur-mats were dominated by filamentous Epsilonproteobacteria or a vibrioid Arcobacter-type. The microbial community of the surface layer was predominantly composed of Epsilonproteobacteria (7-21%), Deltaproteobacteria (20-21%), and Bacteroidetes (19- 20%). Comparative 16S rRNA gene sequence analyses identified various bacteria related to those found in basaltic systems. The presence of an active microbial community in these sediment surface layers was confirmed by high oxygen consumption rates. Geochemical analyses detected metal-sulfides in the sediments, elemental sulfur in the mats and an intensive sulfide flux from below. Ex situ incubations and turnover rate experiments revealed that sulfide is consumed and that sulfate-reduction is performed by the surface sediment microbial community. This was consistent with the detection of aprA-genes and soxB-genes, which are both key genes of the sulfur cycle. Further metabolic capabilities such as denitrification and CO2-fixation were indicated by primary analysis of metagenomic data retrieved by pyrosequencing. So far, our analyses suggest that sulfur cycling is one of the driving forces for primary production and biomass formation in surface sediments of the ultramafic-hosted Logatchev hydrothermal vent fields. Therefore, major differences in microbial composition between basalt- and peridotite-hosted fields were not detected. Hydrothermally influenced sediments from the Mid-Atlantic Ridge and permanently cold sediments from three basins of the eastern South Atlantic Ocean were investigated to examine the ability of microorganisms to disperse in the deep-sea. Besides spatial distance, the structuring effect of the physical barrier Walvis Ridge, which separates the Cape Basin from the other two basins, was determined. The analysis of 16S rRNA gene sequences of the deep- sea sediments revealed phylotypes affiliated with Gammaproteobacteria, Deltaproteobacteria and Acidobacteria, which were present in all three basins. The distribution of these shared phylotypes seemed to be influenced neither by the Walvis Ridge nor by different deep water masses, suggesting a high dispersal capability, as also indicated by low distance decay relationships. In contrast, the comparison of the total bacterial diversity of the cold sediments as well as of the hydrothermally influenced sediments revealed significant differences between the microbial communities. Within the Logatchev field and therefore for small distances (3000 km), both factors influenced bacterial diversity, indicating a complex interplay of local contemporary environmental effects and dispersal limitation

Rheological and Microstructural Changes of Oat and Barley Starches During Heating and Cooling

Microstructural and rheological changes in barley and oat starch dispersions during heating and cooling were studied by light microscopy and dynamic viscoelastic measurements. The two starch pastes showed similar viscoelastic properties after gelatinization, but during cooling the 20% barley starch pastes heated at 95°C underwent a sharp transition in viscoelastic behaviour probably due to the gelation of amylose. This transition was shifted to lower temperatures at 10% starch concentration. Microstructural studies of an 8% barley starch dispersion heated to 90°C using the smear technique showed amylose to form a network structure around the granules. The granules in starch paste heated to 95°C were poorly stained and amylopectin was fragmented. Microscopic examination of an embedded section of the cooled barley starch gel showed amylose to form a continuous phase in which starch granules were dispersed. G\u27 increased below 80°C during cooling of 10% oat starch dispersions preheated at 95 °C. No rheological changes occurred when they were preheated at only 90°C. Microstructural studies of an 8% oat starch dispersion heated to 90°C using the smear technique showed amylose to form a network structure around the granules. Part of the granule structure had already broken down. Heating to 95°C induced considerable changes in the granule structure of oat starch gels. Amylopectin formed a very fine network. Microscopic examination of embedded sections of the cooled, stored gel showed a much coarser structure compared with that of the smear

Interaction of Vibrio cholerae non-O1/non-O139 with Copepods, Cladocerans and Competing Bacteria in the Large Alkaline Lake Neusiedler See, Austria

Vibrio cholerae is a human pathogen and natural inhabitant of aquatic environments. Serogroups O1/O139 have been associated with epidemic cholera, while non-O1/non-O139 serogroups usually cause human disease other than classical cholera. V. cholerae non-O1/non-O139 from the Neusiedler See, a large Central European lake, have caused ear and wound infections, including one case of fatal septicaemia. Recent investigations demonstrated rapid planktonic growth of V. cholerae non-O1/non-O139 and correlation with zooplankton biomass. The aim of this study was to elucidate the interaction of autochthonous V. cholerae with two dominant crustacean zooplankton species in the lake and investigate the influence of the natural bacterial community on this interaction. An existing data set was evaluated for statistical relationships between zooplankton species and V. cholerae and co-culture experiments were performed in the laboratory. A new fluorescence in situ hybridisation protocol was applied for quantification of V. cholerae non-O1/non-O139 cells, which significantly reduced analysis time. The experiments clearly demonstrated a significant relationship of autochthonous V. cholerae non-O1/non-O139 with cladocerans by promoting growth of V. cholerae non-O1/non-O139 in the water and on the surfaces of the cladocerans. In contrast, copepods had a negative effect on the growth of V. cholerae non-O1/non-O139 via competing bacteria from their surfaces. Thus, beside other known factors, biofilm formation by V. cholerae on crustacean zooplankton appears to be zooplankton taxon specific and may be controlled by the natural bacterial community. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00248-010-9764-9) contains supplementary material, which is available to authorized users

Cable bacteria generate a firewall against euxinia in seasonally hypoxic basins

Seasonal oxygen depletion (hypoxia) in coastal bottom waters can lead to the release and persistence of free sulfide (euxinia), which is highly detrimental to marine life. Although coastal hypoxia is relatively common, reports of euxinia are less frequent, which suggests that certain environmental controls can delay the onset of euxinia. However, these controls and their prevalence are poorly understood. Here we present field observations from a seasonally hypoxic marine basin (Grevelingen, The Netherlands), which suggest that the activity of cable bacteria, a recently discovered group of sulfur-oxidizing microorganisms inducing long-distance electron transport, can delay the onset of euxinia in coastal waters. Our results reveal a remarkable seasonal succession of sulfur cycling pathways, which was observed over multiple years. Cable bacteria dominate the sediment geochemistry in winter, whereas, after the summer hypoxia, Beggiatoaceae mats colonize the sediment. The specific electrogenic metabolism of cable bacteria generates a large buffer of sedimentary iron oxides before the onset of summer hypoxia, which captures free sulfide in the surface sediment, thus likely preventing the development of bottom water euxinia. As cable bacteria are present in many seasonally hypoxic systems, this euxinia-preventing firewall mechanism could be widely active, and may explain why euxinia is relatively infrequently observed in the coastal ocean

Складові компоненти мовної особистості в контексті міжкультурної комунікації

Стаття присвячена аналізу складових компонентів мовної особистості в контексті міжкультурної комунікації, їх взаємодії та функціонуванню з точки зору прагматичної спрямованості мовленнєвого впливу. Детально розглядаються три рівні структури мовної особистості (структурно-мовний, лінгвокогнітивний ті мотиваційний) із визначенням специфіки їхніх складових компонентів.Статья посвящена анализу составляющих компонентов языковой личности в контексте межкультурной коммуникаций, их взаимодействию и функционированию с точки зрения прагматической направленности речевого воздействия. Детально рассматриваются три уровня структуры языковой личности (структурно-языковой, лингвокогнитивный и мотивационный) с последующим определением специфики их составляющих компонентов.The article is dedicated to the linguistic personality constituent components' analysis in terms of cross-cultural communication, their interaction and functioning with the speech influence pragmatic orientation taken into consideration. The three levels of the linguistic personality (that is, structural linguistic, lingo cognitive and motivation ones) are under analysis with the following their constituent components specificity determinatio

Induction of autophagy by spermidine promotes longevity.

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Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer‐reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state‐of‐the‐art handbook for basic and clinical researchers.DFG, 389687267, Kompartimentalisierung, Aufrechterhaltung und Reaktivierung humaner Gedächtnis-T-Lymphozyten aus Knochenmark und peripherem BlutDFG, 80750187, SFB 841: Leberentzündungen: Infektion, Immunregulation und KonsequenzenEC/H2020/800924/EU/International Cancer Research Fellowships - 2/iCARE-2DFG, 252623821, Die Rolle von follikulären T-Helferzellen in T-Helferzell-Differenzierung, Funktion und PlastizitätDFG, 390873048, EXC 2151: ImmunoSensation2 - the immune sensory syste