Tag biosphere [29 articles]

Abstract

Methods for error correction and classification of metagenomic datasets suggest that the rare biosphere is not as large as previously assumed. ...

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BACKGROUND:Recent advances in sequencing strategies make possible unprecedented depth and scale of sampling for molecular detection of microbial diversity. Two major paradigm-shifting discoveries include the detection of bacterial diversity that is one to two orders of magnitude greater than previous estimates, and the discovery of an exciting 'rare biosphere' of molecular signatures ('species') of poorly understood ecological significance. We applied a high-throughput parallel tag sequencing (454 sequencing) protocol adopted for eukaryotes to investigate protistan community complexity in two contrasting anoxic marine ...

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Understanding the carbon dynamics of the terrestrial biosphere during climate fluctuations is a prerequisite for any reliable modeling of the climate-carbon cycle feedback. We drive a terrestrial vegetation model with observed climate data to show that most of the fluctuations in atmospheric CO2 are consistent with the modeled shift in the balance between carbon uptake by terrestrial plants and carbon loss through soil and plant respiration. Simulated anomalies of the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) during the last two ...

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Emissions of nonmethane hydrocarbon compounds to the atmosphere from the biosphere exceed those from anthropogenic activity. Isoprene, a five-carbon diene, contributes more than 40% of these emissions. Once emitted to the atmosphere, isoprene is rapidly oxidized by the hydroxyl radical OH. We report here that under pristine conditions isoprene is oxidized primarily to hydroxyhydroperoxides. Further oxidation of these hydroxyhydroperoxides by OH leads efficiently to the formation of dihydroxyepoxides and OH reformation. Global simulations show an enormous flux--nearly 100 teragrams of carbon ...

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When planning a survey of 16S rRNA genes from a complex environment, investigators face many choices including which primers to use and how to taxonomically classify sequences. In this study, we explored how these choices affected a survey of microbial diversity in a sample taken from the aerobic basin of the activated sludge of a North Carolina wastewater treatment plant. We performed pyrosequencing reactions on PCR products generated from primers targeting the V1-V2, V6, and V6-V7 variable regions of the 16S ...

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Anaerobic degradation of organic matter follows similar pathways in digesters and anaerobic freshwater sediments. The responsible microorganisms are linked in a complex food web, where short chain fatty acids and H2 are important intermediates. Degradation of short-chain fatty acids is endothermic under standard conditions and is only possible at low H2 partial pressures maintained by exothermic methanogenesis. The coupling between these endothermic and exothermic processes is delicate, and hence sensitive to environmental changes such as temperature variations. The effect of temperature ...

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With the recent increasing interest in the deep biosphere, the question arises as to where the carbon sources that support deep microbial communities are derived from. Our research was focussed on the water-soluble, low molecular weight (LMW) organic acids that are potentially available from different sedimentary lithologies to serve as a carbon source to feed the deep biosphere. A series of Eocene–Pleistocene coals, mudstones and sandstones of varying rank (maturity) and total organic carbon (TOC) content from the Waikato Basin, New ...

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DNA from low-biodiversity fracture water collected at 2.8-kilometer depth in a South African gold mine was sequenced and assembled into a single, complete genome. This bacterium, Candidatus Desulforudis audaxviator, composes >99.9% of the microorganisms inhabiting the fluid phase of this particular fracture. Its genome indicates a motile, sporulating, sulfate-reducing, chemoautotrophic thermophile that can fix its own nitrogen and carbon by using machinery shared with archaea. Candidatus Desulforudis audaxviator is capable of an independent life-style well suited to long-term isolation from the ...

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Abstract The prokaryotes (bacteria) comprise the bulk of the biomass and chemical activity in sediments. They are well suited to their role as sediment chemists, as they are the right size and have the required metabolic versatility to oxidize the organic carbon in a variety of different ways. The characteristic vertical nutrient (electron donor and electron acceptor) profiles seen in sediments are produced as a result of microbial activities, with each nutrient a product or reactant of one or more metabolic ...

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UNESCO is one of the specialized agencies under the United Nations charged with the advancement and improvement of education, social and natural sciences, culture and communication. This global mandate translates into programmes in the field tailored to the member states' specific requirements that build on the full breadth of expertise available in UNESCO.Environmental awareness building is an integral component of many of UNESCO's programmes. This paper describes how UNESCO addresses the need for awareness building in a variety of settings under ...

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abstract The observed interhemispheric gradient in atmospheric carbon dioxide (CO2) indicates the distribution of CO2 sources and sinks, and for recent decades is evidence of a Northern mid-latitudes sink, a tropical source and southern hemisphere sink. As such, the variability in the gradient also reflects how these fluxes vary with time. However, the variability in the gradient is sensitive to the network of stations used to calculate the gradient. Also, an important consideration when dealing with variability in atmospheric measurements is ...

Abstract

A 13-year (1990–1996, 1999–2004), hourly air CO₂ record measured on a 40 m tower in northern Canada is analyzed against interpolated marine boundary layer CO₂ data representing the free troposphere above the tower. In warmer years, the planetary boundary layer was more depleted with CO₂, suggesting that the land area (10³–10⁴ km²) upwind of the tower sequestered more carbon. After using a novel approach to derive the ...

Abstract

10.1126/science.199.4325.141 ...

Abstract

10.1073/pnas.0605127103 The evolution of marine microbes over billions of years predicts that the composition of microbial communities should be much greater than the published estimates of a few thousand distinct kinds of microbes per liter of seawater. By adopting a massively parallel tag sequencing strategy, we show that bacterial communities of deep water masses of the North Atlantic and diffuse flow hydrothermal vents are one to two orders of magnitude more complex than previously reported for any microbial environment. A relatively ...