Involvement of Bacteria in the Origin of a Newly Described Speleothem in the Gypsum Cave of Grave Grubbo (Crotone, Italy)
| Autor: | Maddalena Del Gallo, Aldo Lepidi, Claudia Ercole, Giogio Cappuccio, Rosita Contento, Paola Cacchio, Maria Preite Martinez |
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| Rok vydání: | 2012 |
| Předmět: |
calcifying bacteria
calcium carbonate speleothem Microorganism speleothems isotopes bacteria Speleothem Mineralogy Stalagmite engineering.material Moonmilk chemistry.chemical_compound Cave Concretion Botany Earth-Surface Processes Calcite geography geography.geographical_feature_category chemistry engineering Carbonate Geology |
| Zdroj: | Journal of Cave and Karst Studies. 74:7-18 |
| ISSN: | 1090-6924 |
| DOI: | 10.4311/2010mb0136r |
| Popis: | Microorganisms have been shown to be important active and passive promoters of redox reactions that influence the precipitation of various minerals, including calcite. Many types of secondary minerals thought to be of purely inorganic origin are currently being reevaluated, and microbial involvement has been demonstrated in the formation of pool fingers, stalactites and stalagmites, cave pisoliths, and moonmilk. We studied the possible involvement of bacteria in the formation of a new type of speleothem from Grave Grubbo Cave, the third-largest gypsum cave in Italy. The speleothem we studied consisted of a large aggregate of calcite tubes having a complex morphology, reflecting its possible organic origin. We isolated an abundant heterotrophic microflora associated with this concretion and identified Bacillus, Burk- holderia ,a ndPasteurella spp. among the isolates. All of the isolates precipitated CaCO3 in vitro in the form of calcite. Only one of the isolates solubilized carbonate. The relative abundance of each isolate was found to be directly related to its ability to precipitate CaCO3 at cave temperature. We suggest that hypogean environments select for microbes exhibiting calcifying activity. Isotopic analysis produced speleothem d 13 C values of about - 5.00%, confirming its organic origin. The lightest carbonates purified from B4M agar plates were produced by the most abundant isolates. SEM analysis of the speleothem showed traces of calcified filamentous bacteria interacting with the substrate. Spherical bioliths predominated among the ones produced in vitro. Within the crystals produced in vitro, we observed bacterial imprints, sometimes in a preferred orientation, suggesting the involvement of a quorum-sensing system in the calcium-carbonate precipitation process. |
| Databáze: | OpenAIRE |
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