Ändra sökning
Avgränsa sökresultatet
1 - 8 av 8
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Ahmed, Engy
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Holmström, Sara J. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Siderophore Production by Microorganisms Isolated From a Podzol Soil Profile2015Ingår i: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 32, nr 5, s. 397-411Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Siderophore-producing bacteria/actinobacteria and fungi were isolated from O- (organic), E- (eluvial), B- (upper illuvial), and C- (parent material) horizons of podzol soil. Siderophores were isolated and hydroxamate type siderophores were detected and quantitated by high-performance liquid chromatography coupled to electrospray ionization mass spectrometry. The molecular identification of siderophore-producing isolates showed that there was a high diversity of fungal and bacterial/actinobacterial species throughout the soil profile. The isolated bacteria/actinobacteria showed different abilities in the production of ferrioxamines (E, B, G and D). Moreover, the isolated fungal species showed great variety in the production of ferrichromes, coprogens and fusarinines.

    Ladda ner fulltext (pdf)
    fulltext
  • 2.
    Ahmed, Engy
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Hugerth, Luisa W.
    Logue, Jurg B.
    Brüchert, Volker
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Andersson, Anders F.
    Holmström, Sara J. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Mineral Type Structures Soil Microbial Communities2017Ingår i: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 34, nr 6, s. 538-545Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Soil microorganisms living in close contact with minerals play key roles in the biogeochemical cycling of elements, soil formation, and plant nutrition. Yet, the composition of microbial communities inhabiting the mineralosphere (i.e., the soil surrounding minerals) is poorly understood. Here, we explored the composition of soil microbial communities associated with different types of minerals in various soil horizons. To this effect, a field experiment was set up in which mineral specimens of apatite, biotite, and oligoclase were buried in the organic, eluvial, and upper illuvial horizons of a podzol soil. After an incubation period of two years, the soil attached to the mineral surfaces was collected, and microbial communities were analyzed by means of Illumina MiSeq sequencing of the 16S (prokaryotic) and 18S (eukaryotic) ribosomal RNA genes. We found that both composition and diversity of bacterial, archaeal, and fungal communities varied across the different mineral surfaces, and that mineral type had a greater influence on structuring microbial assemblages than soil horizon. Thus, our findings emphasize the importance of mineral surfaces as ecological niches in soils.

  • 3.
    Hallberg, Rolf O.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Broman, Curt
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Microbial Fossils in the 2.63 Ga Jeerinah Formation, Western Australia-Evidence of Microbial Oxidation2018Ingår i: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 35, nr 4, s. 255-260Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A diamond drill core from the upper part of the Jeerinah Formation (similar to 2.63 Ga), underlying the Hamersley Group, deposited at a time when the oxygen concentrations in the marine environment were extremely low, was examined for microbial fossils. The paper presents organo-mineral structures in the form of twisted stalks produced by bacteria being present in the laminated black carbonaceous shale sediments. These twisted stalks are organo-mineral structures produced by microaerophilic Fe(II)-oxidizing-type bacteria such as Gallionella and/or Mariprofundus that are active at very low-oxygen concentrations, thus providing evidence for oxygen being present in the marine environment at 2.63 Ga.

  • 4.
    Hallberg, Rolf
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Tai, Cheuk-Wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Multiwall Carbon Nanotubes and Nanofibers in Gallionella2014Ingår i: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 31, nr 9, s. 764-768Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This is a report of microbial formation of multiwall carbon nanotubes (MWCNT) and nanofibers at normal pressure and temperature. Our results demonstrate a single cell organism's ability to form complicated material of high industrial interest. The microorganism, Gallionella, is classified as autotrophic and dysoxic. It uses CO2 for its carbon source and grows in environments with low concentrations of free oxygen. The organisms were taken from a deep bedrock tunnel where water leaking from cracks in the rock formed a precipitate of iron as a bacterial slime on the rock wall. Detailed investigations of the samples by transmission electron microscopy (TEM) revealed several types of MWCNT. The stalk single MWCNT was observed with a diameter of about 10nm and with an inner diameter of 1.35nm. The wall of the nanotube is built by graphite layers. The 10 to 20 sheets are used to form the tubes. The measured spacing between the lines is 0.34nm, which is an average value of interlayer spacing, close to the graphitic distance (0.335nm). HRTEM images reveal a two-dimensional lattice with a spacing of 0.24nm, indicating the presence of graphene.

  • 5. Ivarsson, M.
    et al.
    Bach, W.
    Broman, Curt
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Neubeck, Anna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Bengtson, S.
    Fossilized Life in Subseafloor Ultramafic Rocks2018Ingår i: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 35, nr 6, s. 460-467Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ultramafic rocks are hypothesized to support a subseafloor hydrogen-driven biosphere because of extensive production of bioavailable energy sources like H-2 or CH4 from fluid-rock interactions. Hence, the apparent lack of microbial remains in subseafloor ultramafic rocks, in contrast to their frequent observation in subseafloor basalts, is somewhat of a paradox. Here we report fossilized microbial remains in aragonite veins in ultramafic rocks from the 15 degrees 20N Fracture Zone area on the Mid-Atlantic Ridge (MAR), collected during Ocean Drilling Program (ODP) Leg 209. The microbial remains consist of filamentous structures associated with biofilms. The young age (<1 Myr) and absence of diagenesis result in fossilized microbial communities with a pristine composition characterized by carbonaceous matter (CM) and the enrichment in trace elements such as Ni, Co, Mo and Mn. Our study confirms the presence of the hypothesized deep subseafloor biosphere hosted in ultramafic rocks. We further show that host rock composition may influence the microbial elemental composition, which is recorded during the fossilization.

  • 6. Julies, Elsabe M.
    et al.
    Fuchs, Bernhard M.
    Arnosti, Carol
    Bruchert, Volker
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Organic Carbon Degradation in Anoxic Organic-Rich Shelf Sediments: Biogeochemical Rates and Microbial Abundance2010Ingår i: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 27, nr 4, s. 303-314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Identifying and explaining bottlenecks in organic carbon mineralization and the persistence of organic matter in marine sediments remain challenging. This study aims to illuminate the process of carbon flow between microorganisms involved in the sedimentary microbial food chain in anoxic, organic-rich sediments of the central Namibian upwelling system, using biogeochemical rate measurements and abundances of Bacteroidetes, Gammaproteobacteria, and sulfate-reducing bacteria at two sampling stations. Sulfate reduction rates decreased by three orders of magnitude in the top 20 cm at one sampling station (280 nmol cm-3 d-1 - 0.1 nmol cm-3 d-1) and by a factor of 7 at the second station (65 nmol cm-3 d-1 - 9.6 nmol cm-3 d-1). However, rates of enzymatic hydrolysis decreased by less than a factor of three at both sampling stations for the polysaccharides laminarin (23 nmol cm-3 d-1- 8 nmol cm-3 d-1 and 22 nmol cm-3 d-1- 10 nmol cm-3 d-1) and pullulan (11 nmol cm-3 d-1- 4 nmol cm-3 d-1 and 8 nmol cm-3 d-1- 6 nmol cm-3 d-1). Increasing imbalance between carbon turnover by hydrolysis and terminal oxidation with depth, the steep decrease in cell specific activity of sulfate reducing bacteria with depth, low concentrations of volatile fatty acids (less than 15 M), and persistence of dissolved organic carbon, suggest decreasing bioavailability and substrate limitation with depth.

  • 7.
    Kalinowski, Birgitta E.
    et al.
    Göteborgs universitet.
    Johnsson, Anna
    Göteborgs universitet.
    Arlinger, Johanna
    Göteborgs universitet.
    Pedersen, Karsten
    Göteborgs universitet.
    Ödegaard-Jensen, Arvid
    Chalmers tekniska högskola.
    Edberg, Frida
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för tillämpad miljövetenskap (ITM).
    Microbial mobilization of uranium from shale mine waste2006Ingår i: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 23, nr 3-4, s. 157-164Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The alum shale in the Billingen area in southern Sweden was mined in Ranstad for 5 years during the 1960s. The crushed tailings (processed and unprocessed) were left behind when the Ranstad mine was closed that has caused leaching of metals to the surroundings. The siderophore producing bacterium Pseudomonas fluorescens (sp, SE Sweden) was grown in batch cultures for 5 to 8 days with naturally weathered (unprocessed) uranium ore (0.0029% U by weight), kolm (0.52% U by weight) and acid-leached ore (0.0099% U by weight) in chemically defined media (unbuffered and buffered). Pseudomonas fluorescens grown with ore and unbuffered medium changed the pH from 4.7 to 9.3 and leached out 0.016 to 0.9% (normalized to surface area) of the total amount of U from the different ores. Incubation of the acid-leached ore with bacteria in buffered medium leached out 0.04% of the total U. Uranium was leached out selectively at all conditions, but this could be a pH effect, as pH increased at the same time as the U concentrations did. The observed release of Fe was most likely attributed to the production of microbial siderophores (Fe3+ specific chelators) since Fe3+ has a low solubility at pH > 4. As siderophores contain a number of chelating groups they may still function as complexators even in partly degraded form also for other metals than Fe. Thus, the production of microbial chelators could contribute to the elevated metal concentrations in the drainage water from the closed Ranstad mine, as abiotic processes cannot fully explain these high metal concentrations. In the extension: ligand promoted leaching of toxic elements could also be the key to bioremediation as there is a need for nontoxic cleanup methods for metal contaminated sites.

  • 8.
    Sjöberg, Susanne
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Callac, Nolwenn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper. Swedish Museum of Natural History, Sweden.
    Allard, Bert
    Smittenberg, Rienk H.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Dupraz, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Microbial Communities Inhabiting a Rare Earth Element Enriched Birnessite-Type Manganese Deposit in the Ytterby Mine, Sweden2018Ingår i: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 35, nr 8, s. 657-674Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dominant initial phase formed during microbially mediated manganese oxidation is a poorly crystalline birnessite-type phyllomanganate. The occurrence of manganese deposits containing this mineral is of interest for increased understanding of microbial involvement in the manganese cycle. A culture independent molecular approach is used as a first step to investigate the role of microorganisms in forming rare earth element enriched birnessite-type manganese oxides, associated with water bearing rock fractures in a tunnel of the Ytterby mine, Sweden. 16S rRNA gene results show that the chemotrophic bacterial communities are diverse and include a high percentage of uncultured unclassified bacteria while archaeal diversity is low with Thaumarchaeota almost exclusively dominating the population. Ytterby clones are frequently most similar to clones isolated from subsurface environments, low temperature milieus and/or settings rich in metals. Overall, bacteria are dominant compared to archaea. Both bacterial and archaeal abundances are up to four orders of magnitude higher in manganese samples than in fracture water. Potential players in the manganese cycling are mainly found within the ferromanganese genera Hyphomicrobium and Pedomicrobium, and a group of Bacteroidetes sequences that cluster within an uncultured novel genus most closely related to the Terrimonas. This study strongly suggest that the production of the YBS deposit is microbially mediated.

1 - 8 av 8
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf