Journal: Geobiology

Abbreviation

Publisher

Wiley-Blackwell

Journal Volumes

ISSN

1472-4677
1472-4669

Description

Filters

Reset filters

Search Results

Publications 1 - 10 of 17
  • CaCO3 nucleation by cyanobacteria
    Item type: Journal Article
    Obst, M.; Wehrli, B.; Dittrich, M. (2009)
    Geobiology
  • A hypersaline microbial mat from the Pacific Atoll Kiritimati
    Item type: Journal Article
    Buehring, S. I.; Smittenberg, R. H.; Sachse, D.; et al. (2009)
    Geobiology
  • Record of archaeal activity at the serpentinite-hosted Lost City Hydrothermal Field
    Item type: Journal Article
    Méhay, S,; Früh-Green, Gretchen L.; Lang, S. Q.; et al. (2013)
    Geobiology
  • Nickel and zinc micronutrient availability in Phanerozoic oceans
    Item type: Journal Article
    Sweere, Tim; Dickson, Alexander J.; Vance, Derek (2023)
    Geobiology
    Nickel and zinc are both bio-essential micronutrients with a nutrient-like distribution in the modern ocean, but show key differences in their biological functions and geochemical behavior. Eukaryotic phytoplankton, and especially diatoms, have high Zn quotas, whereas cyanobacteria generally require relatively more Ni. Secular changes in the relative availability of these micronutrients may, therefore, have affected the evolution and diversification of phytoplankton. In this study, we use a large compilation of Ni and Zn concentration data for Phanerozoic sediments to evaluate longterm changes in Ni and Zn availability and possible links to phytoplankton evolution. Modern data suggest that organic-rich sediments capture the dissolved deep ocean Ni/Zn ratio, regardless of local depositional conditions. We use this observation to constrain Ni/Zn ratios for past oceans, based on data from the sedimentary record. This record highlights long-term changes in the relative availability of these micronutrients that can be linked to the (bio)geochemical conditions on the Earth's surface. Early Palaeozoic oceans were likely relatively Ni rich, with sedimentary Ni/Zn ratios for this interval mostly being around similar to 1 or higher. A comparison with Phanerozoic strontium-, carbon-, and sulfur-isotopic records suggests that the late Palaeozoic decrease in sulfidic conditions and increase in hydrothermal inputs and organic-carbon burial rates caused a shift towards more Zn-rich conditions. Mesozoic and Cenozoic sediments show relatively Zn-rich oceans for these time intervals, with sedimentary Ni/Zn ratios mostly being around similar to 1 or lower. These observations imply that the diversification of the dominant groups of modern eukaryotic phytoplankton occurred in relatively Zn-rich oceans and that these organisms still carry this signature in their stoichiometries. However, the Phanerozoic transition to a more Zn-rich ocean predates the origin and diversification of modern eukaryotes and, therefore, this transition was likely not the main direct cause for eukaryotic diversification in the Mesozoic and Cenozoic Eras.
  • Microorganisms, mineral surfaces, and aquatic environments
    Item type: Journal Article
    Dittrich, M.; Luttge, A. (2008)
    Geobiology
  • Copper mobilisation from Cu sulphide minerals by methanobactin: Effect of pH, oxygen and natural organic matter
    Item type: Journal Article
    Rushworth, Danielle D.; Christl, Iso; Kumar, Naresh; et al. (2022)
    Geobiology
    Aerobic methane oxidation (MOx) depends critically on the availability of copper (Cu) as a crucial component of the metal centre of particulate methane monooxygenase, one of the main enzymes involved in MOx. Some methanotrophs have developed Cu acquisition strategies, in which they exude Cu-binding ligands termed chalkophores under conditions of low Cu availability. A well-characterised chalkophore is methanobactin (mb), exuded by the microaerophilic methanotroph Methylosinus trichosporium OB3b. Aerobic methanotrophs generally reside close to environmental oxic-anoxic interfaces, where the formation of Cu sulphide phases can aggravate the limitation of bioavailable Cu due to their low solubility. The reactivity of chalkophores towards such Cu sulphide mineral phases has not yet been investigated. In this study, a combination of dissolution experiments and equilibrium modelling was used to examine the dissolution and solubility of bulk and nanoparticulate Cu sulphide minerals in the presence of mb as influenced by pH, oxygen and natural organic matter. In general, we show that mb is effective at increasing the dissolved Cu concentrations in the presence of a variety of Cu sulphide phases that may potentially limit Cu bioavailability. More Cu was mobilised per mole of mb from Cu sulphide nanoparticles compared with well-crystalline bulk covellite (CuS). In general, the efficacy of mb at mobilising Cu from Cu sulphides is pH-dependent. At lower pH, e.g. pH 5, mb was ineffective at solubilizing Cu. The presence of mb increased dissolved Cu concentrations between pH 7 and 8.5, where the solubility of all Cu sulphides is generally low, both in the presence and absence of oxygen. These results suggest that chalkophore-promoted Cu mobilisation from sulphide phases is an effective extracellular mechanism for increasing dissolved Cu concentrations at oxic-anoxic interfaces, particularly in the neutral to slightly alkaline pH range. This suggests that aerobic methanotrophs may be able to fulfil their Cu requirements via the exudation of mb in natural environments where the bioavailability of Cu is constrained by very stable Cu sulphide phases.
  • The Sedimentary Geochemistry and Paleoenvironments Project
    Item type: Other Journal Item
    Farrell, Úna C.; Samawi, Rifaat; Anjanappa, Savitha; et al. (2021)
    Geobiology
  • Competitive ligand exchange between Cu-humic acid complexes and methanobactin
    Item type: Journal Article
    Pesch, Marie-Laure; Hoffmann, Martin; Christl, Iso; et al. (2013)
    Geobiology
  • Deep-biosphere consortium of fungi and prokaryotes in Eocene subseafloor basalts
    Item type: Journal Article
    Bengtson, S.; Ivarsson, M.; Astolfo, A.; et al. (2014)
    Geobiology
    The deep biosphere of the subseafloor crust is believed to contain a significant part of Earth's biomass, but because of the difficulties of directly observing the living organisms, its composition and ecology are poorly known. We report here a consortium of fossilized prokaryotic and eukaryotic micro-organisms, occupying cavities in deep-drilled vesicular basalt from the Emperor Seamounts, Pacific Ocean, 67.5 m below seafloor (mbsf). Fungal hyphae provide the framework on which prokaryote-like organisms are suspended like cobwebs and iron-oxidizing bacteria form microstromatolites (Frutexites). The spatial inter-relationships show that the organisms were living at the same time in an integrated fashion, suggesting symbiotic interdependence. The community is contemporaneous with secondary mineralizations of calcite partly filling the cavities. The fungal hyphae frequently extend into the calcite, indicating that they were able to bore into the substrate through mineral dissolution. A symbiotic relationship with chemoautotrophs, as inferred for the observed consortium, may be a pre-requisite for the eukaryotic colonization of crustal rocks. Fossils thus open a window to the extant as well as the ancient deep biosphere.
  • Methanogenesis produces strong 13C enrichment in stromatolites of Lagoa Salgada, Brazil: A modern analogue for Palaeo-/Neoproterozoic stromatolites?
    Item type: Journal Article
    Birgel, Daniel; Meister, Patrick; Lundberg, Rebecca; et al. (2015)
    Geobiology
Publications 1 - 10 of 17