Large sulfur bacteria and the formation of phosphorite.
21 Jan 2005-Science (American Association for the Advancement of Science)-Vol. 307, Iss: 5708, pp 416-418
TL;DR: It is shown that apatite abundance in sediments on the Namibian shelf correlates with the abundance and activity of the giant sulfur bacterium Thiomargarita namibiensis, which suggests that sulfur bacteria drive phosphogenesis.
Abstract: Phosphorite deposits in marine sediments are a long-term sink for an essential nutrient, phosphorus. Here we show that apatite abundance in sediments on the Namibian shelf correlates with the abundance and activity of the giant sulfur bacterium Thiomargarita namibiensis, which suggests that sulfur bacteria drive phosphogenesis. Sediments populated by Thiomargarita showed sharp peaks of pore water phosphate ( /=50 grams of phosphorus per kilogram). Laboratory experiments revealed that under anoxic conditions, Thiomargarita released enough phosphate to account for the precipitation of hydroxyapatite observed in the environment.
Citations
More filters
TL;DR: In this article, the authors compared the upwelling and anoxic environments of the C/T black shales and sapropels and concluded that the major driving force for the widespread occurrence of these shales seems to be the increase in volcanic activity and associated CO2-input throughout the Cretaceous.
777 citations
TL;DR: In this article, the authors provide a concise review of the consequences of coastal hypoxia for sediment biogeochemistry, showing that changes in bottom-water oxygen levels have consequences for early diagenetic pathways (more anaerobic at expense of aerobic pathways), the efficiency of reoxidation of reduced metabolites and the nature, direction and magnitude of sediment-water exchange fluxes.
Abstract: The intensity, duration and frequency of coastal hypoxia (oxygen concentration <63µM) are increasing due to human alteration of coastal ecosystems and changes in oceanographic conditions due to global warming. Here we provide a concise review of the consequences of coastal hy- poxia for sediment biogeochemistry. Changes in bottom- water oxygen levels have consequences for early diagenetic pathways (more anaerobic at expense of aerobic pathways), the efficiency of re-oxidation of reduced metabolites and the nature, direction and magnitude of sediment-water exchange fluxes. Hypoxia may also lead to more organic matter accu- mulation and burial and the organic matter eventually buried is also of higher quality, i.e. less degraded. Bottom-water oxygen levels also affect the organisms involved in organic matter processing with the contribution of metazoans de- creasing as oxygen levels drop. Hypoxia has a significant effect on benthic animals with the consequences that ecosys- tem functions related to macrofauna such as bio-irrigation and bioturbation are significantly affected by hypoxia as well. Since many microbes and microbial-mediated biogeo- chemical processes depend on animal-induced transport pro- cesses (e.g. re-oxidation of particulate reduced sulphur and denitrification), there are indirect hypoxia effects on biogeo- chemistry via the benthos. Severe long-lasting hypoxia and anoxia may result in the accumulation of reduced compounds in sediments and elimination of macrobenthic communities with the consequences that biogeochemical properties dur- ing trajectories of decreasing and increasing oxygen may be different (hysteresis) with consequences for coastal ecosys- tem dynamics.
573 citations
Cites background from "Large sulfur bacteria and the forma..."
...Moreover, these giant bacteria also appear to a play a major role in phosphorus cycling as they facilitate formation of authigenic apatites in hypoxic and anoxic sediments (Schulz and Schulz, 2005)....
[...]
TL;DR: This review focuses on the current understanding of microbiology in the dark ocean, outlining salient features of various habitats and discussing known and still unexplored types of microbial metabolism and their consequences in global biogeochemical cycling.
Abstract: The majority of life on Earth--notably, microbial life--occurs in places that do not receive sunlight, with the habitats of the oceans being the largest of these reservoirs. Sunlight penetrates only a few tens to hundreds of meters into the ocean, resulting in large-scale microbial ecosystems that function in the dark. Our knowledge of microbial processes in the dark ocean-the aphotic pelagic ocean, sediments, oceanic crust, hydrothermal vents, etc.-has increased substantially in recent decades. Studies that try to decipher the activity of microorganisms in the dark ocean, where we cannot easily observe them, are yielding paradigm-shifting discoveries that are fundamentally changing our understanding of the role of the dark ocean in the global Earth system and its biogeochemical cycles. New generations of researchers and experimental tools have emerged, in the last decade in particular, owing to dedicated research programs to explore the dark ocean biosphere. This review focuses on our current understanding of microbiology in the dark ocean, outlining salient features of various habitats and discussing known and still unexplored types of microbial metabolism and their consequences in global biogeochemical cycling. We also focus on patterns of microbial diversity in the dark ocean and on processes and communities that are characteristic of the different habitats.
569 citations
TL;DR: In this paper, a new atmospheric pO2 model was proposed that has strong similarities to existing models based on elemental and isotopic mass balances, yet differs in some potentially significant respects.
479 citations
424 citations
References
More filters
TL;DR: PHREEQC as discussed by the authors is a C program written in the C programming language that is designed to perform a wide variety of low-temperature aqueous geochemical calculations.
Abstract: PHREEQC version 2 is a computer program written in the C programming language that is designed to perform a wide variety of low-temperature aqueous geochemical calculations. PHREEQC is based on an ion-association aqueous model and has capabilities for (1) speciation and saturation-index calculations; (2) batch-reaction and onedimensional (1D) transport calculations involving reversible reactions, which include aqueous, mineral, gas, solidsolution, surface-complexation, and ion-exchange equilibria, and irreversible reactions, which include specified mole transfers of reactants, kinetically controlled reactions, mixing of solutions, and temperature changes; and (3) inverse modeling, which finds sets of mineral and gas mole transfers that account for differences in composition between waters, within specified compositional uncertainty limits. New features in PHREEQC version 2 relative to version 1 include capabilities to simulate dispersion (or diffusion) and stagnant zones in 1D-transport calculations, to model kinetic reactions with user-defined rate expressions, to model the formation or dissolution of ideal, multicomponent or nonideal, binary solid solutions, to model fixed-volume gas phases in addition to fixed-pressure gas phases, to allow the number of surface or exchange sites to vary with the dissolution or precipitation of minerals or kinetic reactants, to include isotope mole balances in inverse modeling calculations, to automatically use multiple sets of convergence parameters, to print user-defined quantities to the primary output file and (or) to a file suitable for importation into a spreadsheet, and to define solution compositions in a format more compatible with spreadsheet programs. This report presents the equations that are the basis for chemical equilibrium, kinetic, transport, and inverse modeling calculations in PHREEQC; describes the input for the program; and presents examples that demonstrate most of the program's capabilities.
7,654 citations
TL;DR: In this article, a compilation of marine sedimentary phosphorus burial rates for the last 160 Myr suggests that natural variations have occurred that span one order of magnitude, which suggests that uniform interpretations with respect to the emplacement of major phosphorite deposits should be treated with caution.
694 citations
TL;DR: It would be surprising if some of the variety of poly P functions observed in microorganisms did not apply to aspects of human growth and development, such as aging and the aberrations of disease.
Abstract: Pursuit of the enzymes that make and degrade poly P has provided analytic reagents which confirm the ubiquity of poly P in microbes and animals and provide reliable means for measuring very low concentrations. Many distinctive functions appear likely for poly P, depending on its abundance, chain length, biologic source, and subcellular location. These include being an energy supply and ATP substitute, a reservoir for Pi, a chelator of metals, a buffer against alkali, a channel for DNA entry, a cell capsule and, of major interest, a regulator of responses to stresses and adjustments for survival in the stationary phase of culture growth and development. Whether microbe or human, we depend on adaptations in the stationary phase, which is really a dynamic phase of life. Much attention has been focused on the early and reproductive phases of organisms, which are rather brief intervals of rapid growth, but more concern needs to be given to the extensive period of maturity. Survival of microbial species depends on being able to manage in the stationary phase. In view of the universality and complexity of basic biochemical mechanisms, it would be surprising if some of the variety of poly P functions observed in microorganisms did not apply to aspects of human growth and development, such as aging and the aberrations of disease. Of theoretical interest regarding poly P is its antiquity in prebiotic evolution, which along with its high energy and phosphate content make it a plausible precursor to RNA, DNA, and proteins. Practical interest in poly P includes many industrial applications, among which is its use in the microbial depollution of P1 in marine environments.
531 citations
TL;DR: A previously unknown giant sulfur bacterium is abundant in sediments underlying the oxygen minimum zone of the Benguela Current upwelling system, and is closely related to the marine filamentous sulfur bacteria Thioploca, abundant in the up welling area off Chile and Peru.
Abstract: A previously unknown giant sulfur bacterium is abundant in sediments underlying the oxygen minimum zone of the Benguela Current upwelling system. The bacterium has a spherical cell that exceeds by up to 100-fold the biovolume of the largest known prokaryotes. On the basis of 16S ribosomal DNA sequence data, these bacteria are closely related to the marine filamentous sulfur bacteria Thioploca, abundant in the upwelling area off Chile and Peru. Similar to Thioploca, the giant bacteria oxidize sulfide with nitrate that is accumulated to
445 citations
TL;DR: In this article, the authors describe a massive microbial community which includes organisms typical for sulphide biota, and may have unsuspected importance in the ecology and economy of the sea off western South America.
Abstract: BENTHIC observations off the coast of Chile have consistently disclosed the presence of large coherent microbial communities living at depths of about 50–280 m in the H2S-containing sediments of the shelf in contact with the deoxygenated waters of the Peru–Chile Subsurface Countercurrent (SCC). Similar observations were also made off Peru in 1969 by Gilbert T. Rowe, and in 1976 by G. T. Rowe and John Waterbury of Woods Hole Oceanographic Institution. The microflora, which has only been reported once before in the literature1, has been known for years by the local fishermen who call them estopa (Spanish for uncleansed wool or fiax) due to the filamentous appearance of its main components. In this report I describe this massive microbial community which includes organisms typical for sulphide biota, and may have unsuspected importance in the ecology and economy of the sea off western South America.
254 citations