Bacterial and Archaeal Community Structure of Two Adjacent Calcite Speleothems in Kartchner Caverns, Arizona, USA
2011
Legatzki, Antje | Ortiz, Marian | Neilson, Julia W. | Dominguez, Sky | Andersen, Gary L. | Toomey, Rickard S. | Pryor, Barry M. | Pierson, Leland S. | Maier, Raina M.
Information concerning the bacterial and archaeal communities present on calcite speleothems in carbonate caves is of interest because the activity of these microbes has been implicated as a potential biogenic component in the formation of secondary mineral deposits. In addition, these speleothems may harbor unique, previously unidentified microbes. The current study presents a comparative analysis of the superficial bacterial and archaeal community structure of multiple stalactites from two different cave formations located in close proximity to each other in a nonhuman-impacted area of Kartchner Caverns, Arizona, USA. PCR-denaturing gradient gel electrophoresis analysis (PCR-DGGE) revealed that microbial communities sampled from stalactites of a single speleothem are more similar to each other than to the communities sampled from stalactites of an adjacent speleothem, suggesting that both bacterial and archaeal communities are speleothem-specific. SR-XRD analysis confirmed that both speleothems sampled were primarily calcite, but subtle differences were detected in the elemental composition profiles obtained from ICP-MS analysis indicating that substrate geochemistry was also speleothem-specific. PhyloChip analysis of composite samples from both speleothems revealed a broad diversity of phyla represented in the bacterial communities, while bacterial and archaeal bands sequenced from the DGGE profiles confirmed the presence of unique phylotypes not closely related (< 96% similarity) to any sequences deposited in the GenBank database.
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