Carbonate and Phosphate Precipitation by Chromohalobacter marismortui

13 pages, 6 figures, 2 tables.The ability of Chromohalobacter marismortui to precipitate carbonate and phosphate minerals has been demonstrated for the first time. Mineral precipitation in both solid and liquid media at different salts concentrations and different magnesium/calcium ratios occurred whereas crystal formation was not observed in the control. The precipitated minerals were studied by X-ray diffraction, scanning electron microscopy and EDX, and were different in liquid and solid media. In liquid media aragonite, struvite, vaterite and monohydrocalcite were precipitated forming crystals and bioliths. Bioliths accreted preferentially close to organic pellicles, whereas struvite preferentially grows in microenvironments free of such pellicles. Magnesian calcite, calcian-magnesian kutnahorite, “proto-dolomite” and huntite were formed in solid media. The Mg content of the magnesian calcite and of Ca-Mg kutnahorite also varied depending on the salt concentration of the culture media. This is the first report on bacterial precipitation of Ca-Mg kutnahorite and huntite in laboratory cultures. The results of this research show the active role played by C. marismortui in mineral precipitation, and allow us to compare them with those obtained previously using other taxonomic groups of moderately halophilic bacteria.Peer reviewe

Amorphous Ca-phosphate precursors for Ca-carbonate biominerals mediated by Chromohalobacter marismortui

Although diverse microbial metabolisms are known to induce the precipitation of carbonate minerals, the mechanisms involved in the bacterial mediation, in particular nucleation, are still debated. The study of aragonite precipitation by Chromohalobacter marismortui during the early stages (3-7 days) of culture experiments, and its relation to bacterial metabolic pathways, shows that: (1) carbonate nucleation occurs after precipitation of an amorphous Ca phosphate precursor phase on bacterial cell surfaces and/or embedded in bacterial films; (2) precipitation of this precursor phase results from local high concentrations of PO4 3- and Ca 2+ binding around bacterial cell envelopes; and (3) crystalline nanoparticles, a few hundred nanometres in diametre, form after dissolution of precursor phosphate globules, and later aggregate, allowing the accretion of aragonite bioliths

Bacterial Diversity in Calcium Carbonate Paleo Accretions ( Tosca ) in the Southern Pampas, Argentina

Paleosoil accretions of carbonates in the Tandilia system (Southern Pampas, Argentina) dated to the lower/middle Pleistocene age are locally referred to as tosca. The characterization of this indurated layer of carbonates were analyzed via a biophysicochemical approach, including, physicochemical analysis of soils, mineral x-ray diffraction of the tosca, and microbial diversity of modern soils and tosca layers. The minerals found within tosca were calcite, albite, muscovite, quartz, orthoclase and dolomite in order of most to least abundant. The microbial metataxonomics of tosca was described for the first time. The most abundant microorganisms in tosca were g_Geobacter, g_Pseudonocardia and p_Gemmatimonadetes2 and redundancy analysis of physicochemical parameters and relative microbial abundances revealed positive correlations between Nitrospirae and calcium ions, while mineral and microbial correlations associated Gemmatimonadetes and Firmicutes with calcite and dolomite presence. Magnetospirillum, Geobacter and Bacillus were present in the tosca and the soil above, indicating possible prenucleation sites for calcite and dolomite. Core microorganism abundance was >80% throughout horizons including tosca, hence either microbial entrapment via calcium carbonate precipitation or microbial leaching occurred within this layer.Fil: Pesciaroli, Chiara. Universidad de Granada. Instituto del Agua.; EspañaFil: Purswani, Jessica. Universidad de Granada. Instituto del Agua.; EspañaFil: Mestelan, Silvia. Universidad Nacional del Centro de la Pcia.de Bs.as.. Facultad de Agronomia. Dpto. Cs. Básicas Agronómicas y Biológicas; ArgentinaFil: Lett, Lina. Universidad Nacional del Centro de la Provincia de Buenos Aires; ArgentinaFil: Portela, Gabriela Rut. Universidad Nacional del Centro de la Provincia de Buenos Aires; ArgentinaFil: Medici, Sandra Karina. Universidad Nacional de Mar del Plata. Instituto de Investigaciones en Producción, Sanidad y Ambiente - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Producción, Sanidad y Ambiente; ArgentinaFil: Morillo, Jose Antonio. Consejo Superior de Investigaciones Científicas; EspañaFil: Pozo, Clementina. Universidad de Granada. Instituto del Agua.; EspañaFil: González López, Jesús. Universidad de Granada. Instituto del Agua.; EspañaFil: Rivadeneyra, María Angustias. Universidad de Granada; Españ

Amorphous Ca-phosphate precursors for Ca-carbonate biominerals mediated by Chromohalobacter marismortui

Although diverse microbial metabolisms are known to induce the precipitation of carbonate minerals, the mechanisms involved in the bacterial mediation, in particular nucleation, are still debated. The study of aragonite precipitation by Chromohalobacter marismortui during the early stages (3-7 days) of culture experiments, and its relation to bacterial metabolic pathways, shows that: (1) carbonate nucleation occurs after precipitation of an amorphous Ca phosphate precursor phase on bacterial cell surfaces and/or embedded in bacterial films; (2) precipitation of this precursor phase results from local high concentrations of PO4 3- and Ca 2+ binding around bacterial cell envelopes; and (3) crystalline nanoparticles, a few hundred nanometres in diametre, form after dissolution of precursor phosphate globules, and later aggregate, allowing the accretion of aragonite bioliths