A5042740302- Paleontology and Stratigraphy of Fossils
- Calcium Carbonate Crystallization and Inhibition
- Planetary Science and Exploration
- Geochemistry and Elemental Analysis
- Geology and Paleoclimatology Research
- Astro and Planetary Science
- Microbial Community Ecology and Physiology
- Hydrocarbon exploration and reservoir analysis
- Methane Hydrates and Related Phenomena
- Geomagnetism and Paleomagnetism Studies
- Geological and Geochemical Analysis
- Geochemistry and Geologic Mapping
- Isotope Analysis in Ecology
- Iron oxide chemistry and applications
- Genomics and Phylogenetic Studies
- Protist diversity and phylogeny
- Microbial Fuel Cells and Bioremediation
- Laser-induced spectroscopy and plasma
- Bone Tissue Engineering Materials
- Building materials and conservation
- Microbial Applications in Construction Materials
- Diatoms and Algae Research
- Magnetic and Electromagnetic Effects
- Clay minerals and soil interactions
- Minerals Flotation and Separation Techniques
Institut de minéralogie, de physique des matériaux et de cosmochimie
2016-2025
Centre National de la Recherche Scientifique
2016-2025
Sorbonne Université
2016-2025
Institut de Recherche pour le Développement
2014-2023
Université Sorbonne Nouvelle
2023
Université Paris Cité
2002-2022
Délégation Paris 7
2022
Jet Propulsion Laboratory
2022
Blue Marble Space
2022
Blue Marble Space Institute of Science
2022
Keep It Inside Some cyanobacteria form solid-phase calcium carbonate precipitates as a consequence of fixing CO 2 during photosynthesis. Usually, such carbonates extracellularly near the surface cells, sometimes generating structures called stromatolites. In biofilm growing on deposits in Lake Alchichica, Mexico, Couradeau et al. (p. 459; see Perspective by Riding ) discovered one species that also amorphous particles internally. Because structure and chemical composition these is distinct...
Significance Cyanobacteria are known to promote the precipitation of Ca-carbonate minerals by photosynthetic uptake inorganic carbon. This process has resulted in formation carbonate deposits and a fossil record importance for deciphering evolution cyanobacteria their impact on global carbon cycle. Though mechanisms cyanobacterial calcification remain poorly understood, this is invariably thought as extracellular indirect by-product metabolic activity. Here, we show that contrary common...
Abstract On the NASA 2020 rover mission to Jezero crater, remote determination of texture, mineralogy and chemistry rocks is essential quickly thoroughly characterize an area optimize selection samples for return Earth. As part Perseverance payload, SuperCam a suite five techniques that provide critical complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman Luminescence (TRR/L), visible near-infrared spectroscopy (VISIR), high-resolution color imaging...
The Perseverance rover landed in Jezero crater, Mars, to investigate ancient lake and river deposits. We report observations of the crater floor, below crater's sedimentary delta, finding that floor consists igneous rocks altered by water. lowest exposed unit, informally named Séítah, is a coarsely crystalline olivine-rich rock, which accumulated at base magma body. Magnesium-iron carbonates along grain boundaries indicate reactions with carbon dioxide-rich water under water-poor conditions....
Before Perseverance, Jezero crater's floor was variably hypothesized to have a lacustrine, lava, volcanic airfall, or aeolian origin. SuperCam observations in the first 286 Mars days on revealed and intrusive terrain with compositional density stratification. The dominant lithology along traverse is basaltic, plagioclase enrichment stratigraphically higher locations. Stratigraphically lower, layered rocks are richer normative pyroxene. lowest observed unit has highest inferred olivine-rich...
The geological units on the floor of Jezero crater, Mars, are part a wider regional stratigraphy olivine-rich rocks, which extends well beyond crater. We investigated petrology olivine and carbonate-bearing rocks Séítah formation in Jezero. Using multispectral images x-ray fluorescence data, acquired by Perseverance rover, we performed petrographic analysis Bastide Brac outcrops within this unit. found that these composed igneous rock, moderately altered aqueous fluid. mainly made...
Microbialites are sedimentary deposits associated with microbial mat communities and thought to be evidence of some the oldest life on Earth. Despite extensive studies such deposits, little is known about role microorganisms in their formation. In addition, unambiguous criteria proving biogenicity have yet established. this study, we characterize modern calcareous microbialites from alkaline Lake Van, Turkey, at nanometer scale by combining x-ray electron microscopies. We describe a simple...
The phylogenetic diversity of prokaryotic communities exposed to arid conditions in the hot desert Tataouine (south Tunisia) was estimated with a combination culture and - molecular-based analysis. Thirty-one isolates, representative each dominant morphotypes, were affiliated Actinobacteria, Firmicutes, Proteobacteria CFB group while none related Archaea. Analysis 16S rRNA gene libraries revealed presence species Bacteria Sequences Archaea all non-thermophilic Crenarchaeota subgroup....
Green rust (GR) as highly reactive iron mineral potentially plays a key role for the fate of (in)organic contaminants, such chromium or arsenic, and nitroaromatic compounds functioning both sorbent reductant. GR forms corrosion product steel but is also naturally present in hydromorphic soils sediments forming metastable intermediate during microbial Fe(III) reduction. Although already suggested to form Fe(II) oxidation, clear evidence formation oxidation was lacking. In study, powder XRD,...
ABSTRACT Calcium phosphates and calcium carbonates are among the most prevalent minerals involved in microbial fossilization. Characterization of both organic mineral components biomineralized samples is, however, usually difficult at appropriate spatial resolution (i.e. submicrometer scale). Scanning transmission X‐ray microscopy (STXM) was used to measure C K‐edge, P L‐edge, Ca L‐edge near‐edge absorption fine structure (NEXAFS) spectra some calcium‐containing common biomineralization...
Microbial anaerobic Fe(II) oxidation at neutral pH produces poorly soluble Fe(III) which is expected to bind cell surfaces causing encrustation and potentially impeding metabolism. The challenge for Fe(II)-oxidizing prokaryotes therefore avoid with Fe(III). Using different microscopic techniques we tracked minerals the surface within cells of phylogenetically distinct phototrophic nitrate-reducing bacteria. While some strains successfully prevented others precipitated in periplasm. Our...
ABSTRACT Iron oxidation at neutral pH by the phototrophic anaerobic iron-oxidizing bacterium Rhodobacter sp. strain SW2 leads to formation of iron-rich minerals. These minerals consist mainly nano-goethite (α-FeOOH), which precipitates exclusively outside cells, mostly on polymer fibers emerging from cells. Scanning transmission X-ray microscopy analyses performed C K-edge suggest that these are composed a mixture lipids and polysaccharides or lipopolysaccharides. The iron organic carbon...
Little is known about the production of exopolysaccharides (EPS) in cyanobacteria, and there are no genetic physiological evidences that EPS involved cell protection against frequently encountered environmental stresses caused by salt metals. We studied four presumptive genes, sll0923, sll1581, slr1875 sll5052, model cyanobacterium Synechocystis PCC6803, which produces copious amounts attached to cells (CPS) released culture medium (RPS) as shown here. show sll5052 all dispensable growth...
Abstract In phosphate‐rich environments, vivianite (Fe II 3 (PO 4 ) 2 , 8H O) is an important sink for dissolved Fe(II) and considered as a very stable mineral due to its low solubility at neutral pH. the present study, we report mineralogical transformation of in cultures nitrate‐reducing iron‐oxidizing bacterial strain BoFeN1 presence Fe(II). Vivianite was first transformed into greenish phase consisting mostly amorphous mixed valence Fe‐phosphate. This precipitate became progressively...