title: Role of bacteria in marine barite precipitation: a case study using Mediterranean seawater.
abstract: Marine bacteria isolated from natural seawater were used to test their capacity to promote barite precipitation under laboratory conditions. Seawater samples were collected in the western and eastern Mediterranean at 250 m and 200 m depths, respectively, since marine barite formation is thought to occur in the upper water column. The results indicate that Pseudoalteromonas sp., Idiomarina sp. and Alteromonas sp. actually precipitate barite under experimental conditions. Barite precipitates show typical characteristics of microbial precipitation in terms of size, morphology and composition. Initially, a P-rich phase precipitates and subsequently evolves to barite crystals with low P contents. Under laboratory conditions barite formation correlates with extracellular polymeric substances (EPS) production. Barite precipitates are particularly abundant in cultures where EPS production is similarly abundant. Our results further support the idea that bacteria may provide appropriate microenvironments for mineral precipitation in the water column. Therefore, bacterial production in the past ocean should be considered when using Ba proxies for paleoproductivity reconstructions.
authors: Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR) Av. de las Palmeras 4, 18100 Armilla, Granada, Spain. Electronic address: ntorres@ugr.es.
authors: N
authors: N
authors: Torres-Crespo
authors: Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR) Av. de las Palmeras 4, 18100 Armilla, Granada, Spain. Electronic address: fmruiz@ugr.es.
authors: F
authors: F
authors: Martínez-Ruiz
authors: Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n, 18002 Granada, Spain. Electronic address: mgonzale@ugr.es.
authors: M T
authors: MT
authors: González-Muñoz
authors: Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Profesor Albareda 1, 18008 Granada, Spain. Electronic address: bedmar@eez.csic.es.
authors: E J
authors: EJ
authors: Bedmar
authors: Department of Earth Sciences, Geosciences Faculty, Utrecht University, Budapestlaan 4, P.O. Box 80021, 3584 CD Utrecht, The Netherlands. Electronic address: g.j.delange@uu.nl.
authors: G J
authors: GJ
authors: De Lange
authors: Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n, 18002 Granada, Spain. Electronic address: fadwa@ugr.es.
authors: F
authors: F
authors: Jroundi
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D001466:Barium Sulfate / Q000032:analysis / Q000378:metabolism*; D002980:Climate; D008522:Mediterranean Sea; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S; D012623:Seawater / Q000737:chemistry / Q000382:microbiology*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D001466:Barium Sulfate
keywords: Bacteria; Biomineralization; Marine barite; Microbial processes; Water column