| 1. |
- Amils, R. I., et al.
(author)
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Compact cryogenic wide-band balanced amplifiers with superconducting 90° hybrids for the IF of submillimeter-wave SIS mixers
- 2019
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In: ISSTT 2019 - 30th International Symposium on Space Terahertz Technology, Proceedings Book. ; , s. 57-62
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Conference paper (peer-reviewed)abstract
- The pressing demand for mm-wave cryogenic radio astronomy receivers with increasing instantaneous bandwidth has spurred interest in more complex intermediate frequency amplifier configurations, like the balanced amplifier, as the traditional options have increasing difficulties to comply either with the noise or the input matching specifications. This solution is typically penalized by the slight increment in noise produced by the quadrature hybrid losses. We propose a balanced amplifier using a novel 3 dB quadrature hybrid coupler design with superconducting lines. The prototype unit built for the 4-12 GHz band integrates in the same module the hybrid coupler chips, the low noise amplifiers and the bias circuitry. The mechanical design allows for an independent testing of the individual amplifiers. The average noise temperature is 4.4 K, only 0.3 K more than the average of its amplifiers. The input reflection improves more than 10 dB. This compact balanced amplifier is also compared with a non-integrated version, showing an improvement in noise and reflection. It has been tested in a complete mm-wave receiver, with advantage over other IF schemes.
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| 2. |
- Coustenis, A., et al.
(author)
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TandEM : Titan and Enceladus mission
- 2009
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In: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 23:3, s. 893-946
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Journal article (peer-reviewed)abstract
- TandEM was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini-Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (MontgolfiSre) and possibly several landing probes to be delivered through the atmosphere.
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| 3. |
- Dunér, David, et al.
(author)
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Copernican Principle
- 2021
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In: Encyclopedia of Astrobiology. - Berlin/Heidelberg : Springer Berlin/Heidelberg. ; 1:1, s. 1-3
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Journal article (peer-reviewed)abstract
- The Copernican principle states that Earth has not any privileged position in the universe. In astrobiological terms, it means that terrestrial life, including the human beings, has not any particularly privileged, special, or unique position in the universe, which leads to the assumption that, given the presence of life on Earth, life will exist also in other places in the universe.
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| 4. |
- Dunér, David, et al.
(author)
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Great Chain of Being
- 2021
-
In: Encyclopedia of Astrobiology. - Berlin/Heidelberg : Springer Berlin/Heidelberg. ; 1:1, s. 1-2
-
Journal article (peer-reviewed)abstract
- A prevailing idea through the ages is that of the Great Chain of Being, understanding the universe as a hierarchy of beings, an unbroken chain of existence, from the simplest forms to the most complex ones, from non-living matter to the most rational creatures (Lovejoy 1936). In his History of Animals from the fourth century BCE, Aristotle arranged all beings in a ladder of nature, a scala naturae, a gradation of natural things from minerals, through plants and animals, to the human being. The chain of being got biological significance with, among others, Gottfried Wilhelm Leibniz, Carl Linnaeus, Georges-Louis Leclerc de Buffon, and Charles Bonnet. Nature does not make jumps, Natura non-facit saltus, as Carl Linnaeus formulated it in Philosophia Botanica (1751). There is continuity in nature. In that respect, the Great Chain of Being is connected to the Principle of Plenitude, the fullness of being. The principle suggests that every possible form of creature exists. This could also be understood in a temporal sense that every possible form of creature, even though not existing right now, might have existed before or could be realized at some stage in the future. Continuity is an idea implicit in that of plenitude. In the early nineteenth century, this continuity of nature became understood in temporal meaning. Jean-Baptiste de Lamarck went from a static concept of the series of life-forms to a theory of species transformation that life had developed over time from simpler to more complex forms. During the nineteenth century, the Great Chain of Being was replaced by another metaphor, the Tree of Life, which also stressed on the continuity of nature, but took into account the genealogy and evolution of life-forms, as in Lamarck’s Philosophie zoologique (1809) and Darwin’s Origin of Species (1859).
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| 5. |
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| 6. |
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| 7. |
- Dunér, David, et al.
(author)
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Principle of Plenitude
- 2022
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In: Encyclopedia of Astrobiology. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783642278334 ; 1:1, s. 1-3
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Book chapter (other academic/artistic)
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| 8. |
- Fernández-Remolar, David, et al.
(author)
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A mineralogical archive of the biogeochemical sulfur cycle preserved in the subsurface of the Río Tinto system
- 2018
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In: American Mineralogist. - : Walter de Gruyter. - 0003-004X .- 1945-3027. ; 103:3, s. 394-411
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Journal article (peer-reviewed)abstract
- The search for extinct and extant life on Mars is based on the study of biosignatures that could be preserved under Mars-like, extreme conditions that are replicated in different terrestrial analog environments. The mineral record in the subsurface of the Río Tinto system is one example of a Mars analog site that has been exposed to weathering conditions, including the biogeochemical activity of Fe and S chemolithotrophic bacteria, for millions of years. The SEM-EDAX analysis of different samples recovered in the Peña de Hierro area from four boreholes, ranging from 166 to 610 m in depth, has provided the identification of microbial structures that have affected a suite of hydrothermal minerals (~345 Ma) as well as minerals likely produced by biological activity in more recent times (<7 Ma). The hydrothermal minerals correspond to reduced sulfur or sulfate-bearing compounds (e.g., pyrite and barite) that are covered by bacilli- or filamentous-like microbial structures and/or secondary ferrous carbonates (e.g., siderite) with laminar to spherical structures. The secondary iron carbonates can be in direct contact or above an empty interphase with the primary hydrothermal minerals following a wavy to bent contact. Such an empty interphase is usually filled with nanoscale, straight filamentous structures that have a carbonaceous composition. The occurrence of a sulfur and iron chemolithotrophic community in the Río Tinto basement strongly suggests that the association between sulfur-bearing minerals, dissolution scars and secondary minerals of biological origin is a complex process involving the microbial attack on mineral surfaces by sulfur reducing bacteria followed by the precipitation of iron-rich carbonates. In this scenario, iron sulfide compounds such as pyrite would act as electron donors under microbial oxidation, while sulfate minerals such as barite would act as electron acceptors through sulfate reduction. Furthermore, the formation of siderite would have resulted from carbonate biomineralization of iron chemoheterotrophic organims or other microorganisms that concentrate carbonate through metabolic pathways. Although the distribution of the mineral biosignatures at depth clearly follows a redox gradient, they show some irregular allocation underground, suggesting that the geochemical conditions governing the microbial activity are affected by local changes associated with the fracturing pattern of the Río Tinto basement. The abundance of sulfur- and iron-bearing minerals in the Mars crust suggests that the Río Tinto mineral biosignatures can be useful in the search for extant and extinct subsurface life on the red planet
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| 9. |
- Fernández-Remolar, David C., et al.
(author)
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Preservation of underground microbial diversity in ancient subsurface deposits (>6 ma) of the rio tinto basement
- 2021
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In: Microorganisms. - : MDPI AG. - 2076-2607. ; 9:8
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Journal article (peer-reviewed)abstract
- The drilling of the Rio Tinto basement has provided evidence of an underground microbial community primarily sustained by the Fe and S metabolism through the biooxidation of pyrite orebodies. Although the gossan is the microbial activity product, which dates back to the Oligocene (25 Ma), no molecular evidence of such activity in the past has been reported yet. A Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) molecular analysis of a subsurface sample in the Peña de Hierro basement has provided novel data of the ancient underground microbial community. It shows that the microbial remains are preserved in a mineral matrix composed of laminated Fe-oxysulfates and K-and Na-bearing sulfates alternating with secondary silica. In such a mineral substrate, the biomolecule traces are found in five different microstructure associations, (1) <15 micron-sized nodular microstructures composed of POn(2≤n≤4)−, (2) <30 micron-size mi-cronodules containing fatty acids, acylglycerides, and alkanol chains, (3) <20 micro-sized nodules containing NOn −(2≤n≤3) ions, (4) 40-micron size nodules with NH4+ and traces of peptides, and (5) >200-micron thick layer with N-bearing adducts, and sphingolipid and/or peptide traces. It suggests the mineralization of at least five microbial preserved entities with different metabolic ca-pabilities, including: (1) Acidiphilium/Tessaracoccus-like phosphate mineralizers, (2) microbial patches preserving phosphate-free acylglycerides bacteria, (3) nitrogen oxidizing bacteria (e.g., Acidovorax sp.), (4) traces of heterotrophic ammonifying bacteria, and (5) sphingolipid bearing bacteria (e.g., Sphin-gomonadales, and δ-Proteobacteria) and/or mineralized biofilms. The primary biooxidation process acted as a preservation mechanism to release the inorganic ions that ultimately mineralized the microbial structures.
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| 10. |
- Fernández-Remolar, David C., et al.
(author)
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Productivity contribution of Paleozoic woodlands to the formation of shale hosted massive sulfide deposits in the Iberian Pyrite Belt (Tharsis, Spain)
- 2018
-
In: Journal of Geophysical Research - Biogeosciences. - : John Wiley & Sons. - 2169-8953 .- 2169-8961. ; 123:3, s. 1017-1040
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Journal article (peer-reviewed)abstract
- The geological materials produced during catastrophic and destructive events are an essential source of paleobiological knowledge. The paleobiological information recorded by such events can be rich in information on the size, diversity, and structure of paleocommunities. In this regard, the geobiological study of late Devonian organic matter sampled in Tharsis (Iberian Pyrite Belt) provided some new insights into a Paleozoic woodland community,which was recorded as massive sulfides and black shale deposits affected by a catastrophic event. Sample analysis using TOF-SIMS (Time of Flight Secondary Ion Mass Spectrometer), and complemented by GC/MS (Gas Chromatrograph/Mass Spectrometer) identified organic compounds showing a very distinct distribution in the rock. While phytochemical compounds occur homogeneously in the sample matrix that is composed of black shale, the microbial-derived organics are more abundant in the sulfide nodules. The co-occurrence of sulfur bacteria compounds and the overwhelming presence of phytochemicals provide support for the hypothesis that the formation of the massive sulfides resulted from a high rate of vegetal debris production and its oxidation through sulfate reduction under suboxic to anoxic conditions. A continuous supply of iron from hydrothermal activity coupled with microbial activity was strictly necessary to produce this massive orebody. A rough estimate of the woodland biomass was made possible by accounting for the microbial sulfur production activity recorded in the metallic sulfide. As a result, the biomass size of the late Devonian woodland community was comparable to modern woodlands like the Amazon or Congo rainforests.
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| 11. |
- Fernández-Remolar, David C., et al.
(author)
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Unveiling microbial preservation under hyperacidic and oxidizing conditions in the Oligocene Rio Tinto deposit
- 2021
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 11:1
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Journal article (peer-reviewed)abstract
- The preservation of biosignatures on Mars is largely associated with extensive deposits of clays formed under mild early Noachian conditions (> 3.9 Ga). They were followed by widespread precipitation of acidic sulfates considered adverse for biomolecule preservation. In this paper, an exhaustive mass spectrometry investigation of ferric subsurface materials in the Rio Tinto gossan deposit (~ 25 Ma) provides evidence of well-preserved molecular biosignatures under oxidative and acidic conditions. Time of flight secondary ion mass spectrometry (ToF–SIMS) analysis shows a direct association between physical-templating biological structures and molecular biosignatures. This relation implies that the quality of molecular preservation is exceptional and provides information on microbial life formerly operating in the shallow regions of the Rio Tinto subsurface. Consequently, low-pH oxidative environments on Mars could also record molecular information about ancient life in the same way as the Noachian clay-rich deposits.
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| 12. |
- Gurvits, L. I., et al.
(author)
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The science case and challenges of spaceborne sub-millimeter interferometry: the study case of TeraHertz Exploration and Zooming-in for Astrophysics (THEZA)
- 2021
-
In: Proceedings of the International Astronautical Congress, IAC. - 0074-1795. ; A7
-
Conference paper (peer-reviewed)abstract
- Ultra-high angular resolution in astronomy has always been an important vehicle for making fundamental discoveries. Recent results in direct imaging of the vicinity of the super-massive black hole in the nucleus of the radio galaxy M87 by the millimeter VLBI system Event Horizon Telescope (EHT) and various pioneering results of the Space VLBI mission RadioAstron provided new momentum in high angular resolution astrophysics. In both mentioned cases, the angular resolution reached the values of about 10−20 microrcseconds (0.05−0.1 nanoradian). Angular resolution is proportional to the observing wavelength and inversely proportional to the interferometer baseline length. In the case of Earth-based EHT, the highest angular resolution was achieved by combining the shortest possible wavelength of 1.3 mm with the longest possible baselines, comparable to the Earth’s diameter. For RadioAstron, operational wavelengths were in the range from 92 cm down to 1.3 cm, but the baselines were as long as ∼350,000 km. However, these two highlights of radio astronomy, EHT and RadioAstron do not”saturate” the interest to further increase in angular resolution. Quite opposite: the science case for further increase in angular resolution of astrophysical studies becomes even stronger. A natural and, in fact, the only possible way of moving forward is to enhance mm/sub-mm VLBI by extending baselines to extraterrestrial dimensions, i.e. creating a mm/sub-mm Space VLBI system. The inevitable move toward space-borne mm/sub-mm VLBI is a subject of several concept studies. In this presentation we will focus on one of them called TeraHertz Exploration and Zooming-in for Astrophysics (THEZA), prepared in response to the ESA’s call for its next major science program Voyage 2050 (Gurvits et al. 2021). The THEZA rationale is focused at the physics of spacetime in the vicinity of super-massive black holes as the leading science drive. However, it will also open up a sizable new range of hitherto unreachable parameters of observational radio astrophysics and create a multi-disciplinary scientific facility and offer a high degree of synergy with prospective “single dish” space-borne sub-mm astronomy (e.g., Wiedner et al. 2021) and infrared interferometry (e.g., Linz et al. 2021). As an amalgam of several major trends of modern observational astrophysics, THEZA aims at facilitating a breakthrough in high-resolution high image quality astronomical studies.
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| 13. |
- Gurvits,, et al.
(author)
-
The science case and challenges of space-borne sub-millimeter interferometry
- 2022
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In: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 196, s. 314-333
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Journal article (peer-reviewed)abstract
- Ultra-high angular resolution in astronomy has always been an important vehicle for making fundamental discoveries. Recent results in direct imaging of the vicinity of the supermassive black hole in the nucleus of the radio galaxy M87 by the millimeter VLBI system Event Horizon Telescope and various pioneering results of the Space VLBI mission RadioAstron provided new momentum in high angular resolution astrophysics. In both mentioned cases, the angular resolution reached the values of about 10???20 microarcseconds (0.05???0.1 nanoradian). Further developments towards at least an order of magnitude ???sharper???values, at the level of 1 microarcsecond are dictated by the needs of advanced astrophysical studies. The paper emphasis that these higher values can only be achieved by placing millimeter and submillimeter wavelength interferometric systems in space. A concept of such the system, called Terahertz Exploration and Zooming-in for Astrophysics, has been proposed in the framework of the ESA Call for White Papers for the Voyage 2050 long term plan in 2019. In the current paper we present new science objectives for such the concept based on recent results in studies of active galactic nuclei and supermassive black holes. We also discuss several approaches for addressing technological challenges of creating a millimeter/sub-millimeter wavelength interferometric system in space. In particular, we consider a novel configuration of a space-borne millimeter/sub-millimeter antenna which might resolve several bottlenecks in creating large precise mechanical structures. The paper also presents an overview of prospective space-qualified technologies of low-noise analogue front-end instrumentation for millimeter/sub-millimeter telescopes. Data handling and processing instrumentation is another key technological component of a sub-millimeter Space VLBI system. Requirements and possible implementation options for this instrumentation are described as an extrapolation of the current state-of-the-art Earth-based VLBI data transport and processing instrumentation. The paper also briefly discusses approaches to the interferometric baseline state vector determination and synchronisation and heterodyning system. The technology-oriented sections of the paper do not aim at presenting a complete set of technological solutions for sub-millimeter (terahertz) space-borne interferometers. Rather, in combination with the original ESA Voyage 2050 White Paper, it sharpens the case for the next generation microarcsecond-level imaging instruments and provides starting points for further in-depth technology trade-off studies.
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| 14. |
- Persson, Erik, et al.
(author)
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Astrobiology as Science
- 2021. - 3
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In: Encyclopedia of Astrobiology. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783642278334 - 9783642278334
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Book chapter (other academic/artistic)abstract
- “Astrobiology as science” refers to how astrobiology is characterized and discussed in the philosophy of science.
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| 15. |
- Westmeijer, George, et al.
(author)
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Continental scientific drilling and microbiology : (extremely) low biomass in bedrock of central Sweden
- 2024
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In: Biogeosciences. - : Copernicus Publications. - 1726-4170 .- 1726-4189. ; 21:2, s. 591-604
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Journal article (peer-reviewed)abstract
- Scientific drilling expeditions offer a unique opportunity to characterize microbial communities in the subsurface that have long been isolated from the surface. With subsurface microbial biomass being low in general, biological contamination from the drilling fluid, sample processing, or molecular work is a major concern. To address this, characterization of the contaminant populations in the drilling fluid and negative extraction controls are essential for assessing and evaluating such sequencing data. Here, rock cores down to 2250 m depth, groundwater-bearing fractures, and the drilling fluid were sampled for DNA to characterize the microbial communities using a broad genomic approach. However, even after removing potential contaminant populations present in the drilling fluid, notorious contaminants were abundant and mainly affiliated with the bacterial order Burkholderiales. These contaminant microorganisms likely originated from the reagents used for isolating DNA despite stringent quality standards during the molecular work. The detection of strictly anaerobic sulfate reducers such as Candidatus Desulforudis audaxviator suggested the presence of autochthonous deep biosphere taxa in the sequenced libraries, yet these clades represented only a minor fraction of the sequence counts ( < 0.1 %), hindering further ecological interpretations. The described methods and findings emphasize the importance of sequencing extraction controls and can support experimental design for future microbiological studies in conjunction with continental drilling operations.
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| 16. |
- Westmeijer, George, et al.
(author)
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Continental scientific drilling and microbiology: (extremely) low biomass in crystalline bedrock of central Sweden
- 2023
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Other publication (other academic/artistic)abstract
- Scientific drilling expeditions offer a unique opportunity to characterize the microbial communities in the subsurface that have been long-term isolated from the surface. With subsurface microbial biomass being low in general, biological contamination from the drilling fluid, sample processing, or molecular work is a major concern. To address this, characterization of the contaminant populations in the drilling fluid and negative extraction controls are essential for assessing and evaluating such sequencing data. Here, crystalline rock cores down to 2250 m depth, groundwater-bearing fractures, and the drilling fluid were sampled for DNA to characterize the microbial communities using a broad genomic approach. However, even after removing potential contaminant populations present in the drilling fluid, notorious contaminants were abundant and mainly affiliated with the bacterial order Burkholderiales. These contaminant microorganisms likely originated from the reagents used for isolating and amplifying DNA despite stringent quality standards during the molecular work. The detection of strictly anaerobic sulfate reducers such as Candidatus Desulforudis audaxviator suggested the presence of autochthonous deep biosphere taxa in the sequenced libraries, yet these clades represented only a minor fraction of the sequence counts (< 0.1 %), hindering further ecological interpretations. The described methods and findings emphasize the importance of sequencing extraction controls and can support experimental design for future microbiological studies in conjunction with continental drilling operations.
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| 17. |
- Wu, Xiaofen
(author)
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Structure and function of microbial communities in acid sulfate soil and the terrestrial deep biosphere
- 2016
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Doctoral thesis (other academic/artistic)abstract
- This thesis describes the use of different DNA sequencing technologies to investigate the structure and function of microbial communities in two extreme environments, boreal acid sulfate soil and the terrestrial deep biosphere.The first of the two investigated environments was soils containing un-oxidized metal sulfides that are termed ‘potential acid sulfate soil’ (PASS) materials. If these materials are exposed to atmospheric oxygen by either natural phenomena (e.g., land uplift) or human activities (e.g., drainage) then the metal sulfides become oxidized and the PASS becomes acidic and is defined as an ‘acid sulfate soil’ (ASS). The resulting acid and metal release from metal sulfide oxidation can lead to severe environmental damage. Although acidophilic microorganisms capable of catalyzing acid and metal release have been identified from many sulfide mineral containing environments, the microbial community of boreal PASSs/ASSs remains unclear. This study investigated the physicochemical and microbial characteristics of PASSs and ASSs from the Risöfladan experimental field in Vasa, Finland. Sanger sequencing of 16S rRNA gene sequences of microorganisms present in the PASSs and ASSs were mostly assigned to acidophilic species and environmental clones previously identified from acid- and metal-contaminated environments. Enrichment cultures inoculated from the ASS demonstrated that the acidophilic microorganisms were responsible for catalyzing acid and metal release from PASSs/ASSs. Lastly, the study investigated how to mitigate metal sulfide oxidation and the concomitant formation of sulfuric acid by treating ASSs in situ with CaCO3 or Ca(OH)2 suspensions. The DNA sequencing still identified acidophilic microorganisms after the chemical treatments. However, the increased pH during and after treatment suggested that the activity of the acidophiles might be inhibited. This study was the first to identify the microbial community present in boreal PASSs/ASSs and suggested that treatment with basic compounds may inhibit microbial catalysis of metal sulfide dissolution.The second studied environment was the deep, dark terrestrial subsurface that is suggested to be both extremely stable and highly oligotrophic. Despite the scarcity of carbon and energy sources, the deep biosphere is estimated to constitute up to 20% of the total biomass on earth and thus, represents the largest microbial ecosystem. However, due to the difficulties of accessing this environment and our inability to cultivate the indigenous microbial populations, details of the diversity and metabolism of these communities remain largely unexplored. This study was carried out at Äspö Hard Rock Laboratory, Sweden and utilized second-generation sequencing to identify the taxonomic composition and genetic potential of planktonic and biofilm populations. Community DNA sequencing of planktonic cells from three water types at varied age and depth (‘modern marine’, ‘undefined mixed’, and ‘old saline’) showed the existence of ultra-small cells capable of passing through a 0.22 μm filter that were phylogenetically distinct communities from the >0.22 μm fraction. The reduced cell size and/or genome size suggested a potential adaptation to the oligotrophic environment in the terrestrial deep biosphere. The identified planktonic communities were dominated by Proteobacteria, Candidate divisions, unclassified archaea, and unclassified bacteria. Functional analysis of the assembled genomes showed that the planktonic population from the shallow modern marine water demonstrated a predominantly anaerobic and heterotrophic lifestyle. In contrast, the deeper, old saline water was more closely aligned with the hypothesis of a hydrogen-driven deep biosphere. Metagenomic analysis of subsurface biofilms from ‘modern marine’ and ‘old saline’ water types suggested only a subset of populations were involved in initial biofilm formation. The identified biofilm populations from both water types were distinct from the planktonic community and were suggested to be dominated by hydrogen fed, chemolithoautotrophic and diazotrophic populations.
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