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Micro-scale in situ characterisation of the organic and mineral composition of modern, hypersaline, photosynthetic microbial mats

hal.structure.identifierInstitut des Sciences de la Terre d'Orléans - UMR7327 [ISTO]
dc.contributor.authorGAUTRET, Pascale
hal.structure.identifierInstitut des Sciences de la Terre d'Orléans - UMR7327 [ISTO]
dc.contributor.authorRAMBOZ, Claire
hal.structure.identifierEcosystèmes lagunaires : organisation biologique et fonctionnement [ECOLAG]
dc.contributor.authorDE WIT, R.
hal.structure.identifierInstitut des Sciences de la Terre d'Orléans - UMR7327 [ISTO]
dc.contributor.authorDELARUE, Frédéric
dc.contributor.authorORANGE, François
hal.structure.identifierCentre d'Etudes Nucléaires de Bordeaux Gradignan [CENBG]
dc.contributor.authorSORIEUL, S.
hal.structure.identifierCentre de biophysique moléculaire [CBM]
dc.contributor.authorWESTALL, Francès
dc.date.conference2012-04-22
dc.description.abstractEnPhysico-chemical and biological micro-scale environmental parameters within microbial mats formed in hypersaline conditions favour the precipitation of minerals, such as carbonates. We used optical microscopy and the technique "Fluorescence Induction Relaxation " (FIRe) to differentiate the photosynthetic activity of oxygenic photosynthesisers (cyanobacteria) from anoxygenic photosynthesisers (Chloroflexus-like bacteria, CFB) in samples obtained in 2011. After this preliminary investigation, we characterised the elemental composition of the different species of microorganisms, their extracellular substances (EPS), and the minerals precipitated on their surface. This study was made in-situ by µ-PIXE using the nuclear microprobe of the AIFIRA platform (CEN Bordeaux-Gradignan ; protons of 1.5 or 3MeV). With this microprobe it is possible to map the distribution of elements occurring in quantities down to several ppm, a resolution that is particularly favourable for studying microorganisms. SEM observation of the same zones allowed us to localise exactly the microbial structures (cells, EPS) and minerals analysed by nuclear probe. We were thus able to document the differential S and P concentrations in the different microbial species, the CLB being richer in P. Note that the CLB filaments are < 1 µm in diameter. We were also able to demonstrate the anti-correlation of Ca and Mg in the minerals precipitated directly on the microorganisms and on their EPS. Thus we have shown the utility of these in situ, nano-scale methods in studying microbial structures consisting of different species with different metabolic activitie, and different functional groups on their cell walls and EPS implicated in the bioprecipitation of different kinds of minerals. Such features in ancient microbial mats could aid their interpretation and possibly the distinction between ancient oxygenic and anoxygenic mats.
dc.language.isoen
dc.title.enMicro-scale in situ characterisation of the organic and mineral composition of modern, hypersaline, photosynthetic microbial mats
dc.typeCommunication dans un congrès
dc.subject.halPlanète et Univers [physics]/Interfaces continentales, environnement
dc.subject.halSciences de l'environnement/Milieux et Changements globaux
bordeaux.countryAT
bordeaux.conference.cityVienne
bordeaux.peerReviewedoui
hal.identifierinsu-00840595
hal.version1
hal.invitednon
hal.proceedingsnon
hal.conference.end2012-04-27
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//insu-00840595v1
bordeaux.COinSctx_ver=Z39.88-2004&amp;rft_val_fmt=info:ofi/fmt:kev:mtx:journal&amp;rft.au=GAUTRET,%20Pascale&amp;RAMBOZ,%20Claire&amp;DE%20WIT,%20R.&amp;DELARUE,%20Fr%C3%A9d%C3%A9ric&amp;ORANGE,%20Fran%C3%A7ois&amp;rft.genre=unknown


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