title: Biomineralization of carbonates by Marinococcus albus and Marinococcus halophilus isolated from the Salar de Atacama (Chile).
abstract: We studied the precipitation of carbonates in 17 strains of moderately halophilic, Gram-positive cocci belonging to two species: Marinococcus halophilus and Marinococcus albus, isolated from the Salar de Atacama (Chile). They were cultivated in solid and liquid laboratory media for 42 days at salt concentrations (wt/vol) of 3%, 7.5%, 15%, and 20%. The bioliths precipitated were studied by X-ray diffraction and scanning electron microscopy. M. halophilus formed crystals at each of the salt concentrations, with a maximum number of strains capable of precipitating carbonates at 7.5% and 15% salt concentrations. M. albus did not precipitate at 20% and showed a maximum at 7.5%. This behavior is similar to that of other gram-positive bacteria and differs from that found in gram-negative bacteria. The bioliths precipitated were spherical, generally isolated, with a size of 10-100 microm, varying with salinity. They were of magnesium calcite (CO3 Ca1-x Mgx) with Mg content increasing with increasing salinity and Mg/Ca molar ratio of the culture medium. These results demonstrate the active role played by M. halophilus and M. albus in the precipitation of carbonates.
authors.affiliation: Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071-Granada, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Rivadeneyra
authors.forename: G
authors.initials: G
authors.lastname: Delgado
authors.forename: M
authors.initials: M
authors.lastname: Soriano
authors.forename: A
authors.initials: A
authors.lastname: Ramos-Cormenzana
authors.forename: R
authors.initials: R
authors.lastname: Delgado
mesh_terms: D002254:Carbonates / Q000378:metabolism*; D002677:Chile; D003460:Crystallization; D003470:Culture Media / Q000737:chemistry; D006095:Gram-Positive Cocci / Q000254:growth & development / Q000378:metabolism*; D015636:Magnesium Chloride / Q000737:chemistry; D017616:Magnesium Compounds / Q000378:metabolism; D012965:Sodium Chloride / Q000737:chemistry; D013997:Time Factors
chemical_list: D002254:Carbonates; D003470:Culture Media; D017616:Magnesium Compounds; D015636:Magnesium Chloride; D012965:Sodium Chloride