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  • 1
    Electronic Resource
    Electronic Resource
    Quantitative analysis of bacterial communities from Mediterranean sapropels based on cultivation-dependent methods (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 51 (2004), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Microbial communities of ancient Mediterranean sapropels, buried sediment layers of high organic matter, were analyzed by most probable number (MPN) approaches. Mineral media containing different carbon sources in sub-millimolar concentrations were used. MPN numbers were elevated in sapropels and at the sediment surface, which mirrored total cell count distributions. Highest MPN counts were obtained with a mixture of different monomeric and polymeric substrates, with amino acids or with long-chain fatty acids as sole carbon sources. These values reached up to 2 × 107 cm−3, representing 3.3% of the total cell count. A total of 98 pure cultures were isolated from the highest positive dilutions of the MPN series, representing the most abundant microorganisms culturable by the methods used. The strains were identified by molecular biological methods and could be grouped into 19 different phylotypes. They belonged to the α-, β-, γ-, and δ-Proteobacteria, to the Actinobacteria and the Firmicutes. However, about half of the number of isolates was closely related to the genera Photobacterium and Agrobacterium. Regarding the high cultivation success, these organisms can be assumed to be typical sapropel bacteria, representing a substantial part of the culturable indigenous microbial community.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/j.femsec.2004.07.010
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Vertical distribution of sulfate-reducing bacteria at the oxic-anoxic interface in sediments of the oligotrophic Lake Stechlin (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 22 (1997), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Vertical distribution of sulfate-reducing bacteria (SRB) and sulfate reduction rates were investigated in littoral and profundal sediments of the oligotrophic Lake Stechlin. SRB counted by the most probable number (MPN) technique showed two peaks, one at the oxic-anoxic interface, and the second deeper in the reduced sediment layer. Sulfate reduction rates determined as potential rates in anoxic sediment slurries showed a similar vertical distribution with the highest values in the anoxic zones. The highest cell numbers observed were 1.3×105 cells cm−3 with lactate as substrate. SRB were also found in oxic sediment layers in numbers similar to those detected in anoxic zones. From the highest positive MPN tubes 34 pure cultures were isolated. Physiological characterization including nutritional behaviour, tests for desulfoviridin and spore formation turned out that nearly all isolates belonged to the genera Desulfovibrio, Desulfomicrobium, and Desulfotomaculum. SRB from the oxic sediment layers revealed a higher oxygen tolerance and capacity of oxygen respiration than isolates from the anoxic sediment layers. However, no sulfate reduction was observed in the presence of oxygen, since oxygen was preferentially reduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.1997.tb00377.x
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  • 3
    Electronic Resource
    Electronic Resource
    Growth and chemosensory behavior of sulfate-reducing bacteria in oxygen–sulfide gradients (2002)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 40 (2002), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Growth and chemotactic behavior in oxic–anoxic gradients were studied with two freshwater and four marine strains of sulfate-reducing bacteria related to the genera Desulfovibrio, Desulfomicrobium or Desulfobulbus. Cells were grown in oxygen–sulfide counter-gradients within tubes filled with agar-solidified medium. The immobilized cells grew mainly in the anoxic zone, revealing a peak below the oxic–anoxic interface. All tested strains survived exposure to air for 8 h and all were capable of oxygen reduction with lactate. Most strains also oxidized sulfide with oxygen. Desulfovibrio desulfuricans responded chemotactically to lactate, nitrate, sulfate and thiosulfate, and even sulfide functioned as an attractant. In oxic–anoxic gradients the bacteria moved away from high oxygen concentrations and formed bands at the outer edge of the oxic zone at low oxygen concentration (〈5% O2 saturation). They were able to actively change the extension and slope of the gradients by oxygen reduction with lactate or even sulfide as electron donor. Generally, the chemotactic behavior was in agreement with a defense strategy that re-establishes anoxic conditions, thus promoting anaerobic growth and, in a natural community, fermentative production of the preferred electron donors of the sulfate-reducing bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.2002.tb00935.x
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  • 4
    Electronic Resource
    Electronic Resource
    The ecological niche of the consortium “Pelochromatium roseum” (1998)
    Springer
    Archives of microbiology 169 (1998), S. 120-128 
    Details
    ISSN: 1432-072X
    Keywords: Key words Phototrophic consortia ; Green sulfur ; bacteria ; Chlorobiaceae ; “Chlorochromatium” ; “Pelochromatium” ; Syntrophy ; Sulfur cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A dense accumulation of the phototrophic consortium “Pelochromatium roseum” in a small, eutrophic, freshwater lake (Dagowsee, Brandenburg, Germany) was investigated. Within the chemocline, the number of epibionts of the consortia represented up to 19% of the total number of bacteria. Per “P. roseum” a mean value of 20 epibionts was determined. Similar to other aquatic habitats, consortia in the Dagowsee were found only at low light intensities (〈 7 μmol quanta m–2 s–1) and low sulfide concentrations (0–100 μM). In dialysis cultures of “P. roseum”, bacterial cells remained in a stable association only when incubated at light intensities between 5 and 10 μmol quanta m–2 s–1. Intact consortia from natural samples had a buoyant density of 1046.8 kg m–3, which was much higher than that of ambient chemocline water (995.8 kg m–3). Under environmental conditions and without motility, this density difference would result in rapid sedimentation of consortia toward the lake bottom. Our results indicate that (1) consortia are adapted to a very narrow regime of light intensities and sulfide concentrations, (2) motility and tactic responses must be of ecological significance for the colonization of the free water column of lakes, and (3) phototrophic growth of consortia can be explained only by a cycling of sulfur species in the chemocline, possibly within the consortia themselves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050551
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  • 5
    Electronic Resource
    Electronic Resource
    High genetic and physiological diversity of sulfate-reducing bacteria isolated from an oligotrophic lake sediment (1998)
    Springer
    Archives of microbiology 170 (1998), S. 243-251 
    Details
    ISSN: 1432-072X
    Keywords: Key words Sulfate-reducing bacteria ; Molecular ; fingerprinting ; Bacterial diversity ; Culturability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The community structure of sulfate-reducing bacteria in littoral and profundal sediments of the oligotrophic Lake Stechlin (Germany) was investigated. A collection of 32 strains was isolated from the highest positive dilutions of most-probable-number series, and their partial 16S rRNA gene sequences and genomic fingerprints based on ERIC (enterobacterial repetitive intergenic consensus)-PCR were analyzed. The strains fell into eight distinct phylogenetic lineages, and the majority (70%) showed a close affiliation to the genus Desulfovibrio. Most of the remaining strains (22%) were related to the gram-positive Sporomusa and Desulfotomaculum groups. A high redundancy of 16S rRNA gene sequences was found within several of the phylogenetic lineages. This low phylogenetic diversity was most pronounced for the subset of strains isolated from oxic sediment layers. ERIC-PCR revealed that most of the strains with identical 16S rRNA gene sequences were genetically different. Since strains with identical 16S rRNA gene sequences but different genomic fingerprints also differed considerably with respect to their physiological capabilities, the high diversity detected in the present work is very likely of ecological relevance. Our results indicate that a high diversity of sulfate-reducing bacterial strains can be recovered from the natural environment using the established cultivation media.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050639
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  • 6
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    New insights into large-scale trends in apparent organic matter reactivity in marine sediments and patterns of benthic carbon ttansformation (2021)
    COPERNICUS GESELLSCHAFT MBH
    In:  EPIC3Biogeosciences, COPERNICUS GESELLSCHAFT MBH, 18(15), pp. 4651-4679, ISSN: 1726-4170
    Details
    Publication Date: 2021-08-26
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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    PAPER (OA)
  • 7
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    Prokaryotes stimulate mineral H2 formation for the deep biosphere and subsequent thermogenic activity (2011)
    Geological Society of America (GSA)
    Details
    Publication Date: 2011-03-01
    Description: The deep subseafloor biosphere contains two-thirds of Earth's prokaryotic biomass, which may indicate the presence of novel mechanisms of energy generation as temperatures increase in the subsurface. In sediment slurry experiments (0-100 {degrees}C) with a range of common minerals and rocks (including basalt and quartz), there is significant H2 formation at elevated temperatures, but only in the presence of prokaryotes. This stimulates further prokaryotic activity, typical of deep sediments (sulfate reduction, acetogenesis, and CO2 production, plus continuing methanogenesis), and Bacteria and Archaea representative of many deep sediment types develop. H2 and acetate formation is particularly stimulated above 70 {degrees}C. This prokaryotic activity even enhances reactions when temperatures are raised to thermogenic levels ([~]125-155 {degrees}C), including hydrocarbon generation. Mechanochemistry may be important for mineral H2 formation; this is enhanced by prokaryotes (biomechanochemistry), and subsurface stress and fracturing, which is widespread on Earth.
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
    Published by Geological Society of America (GSA)
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