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Astrobiology. Sep 2011; 11(7): 601–618.
PMCID: PMC3176350
Lava Cave Microbial Communities Within Mats and Secondary Mineral Deposits: Implications for Life Detection on Other Planets
D.E. Northup,corresponding author1 L.A. Melim,2 M.N. Spilde,3 J.J.M. Hathaway,1 M.G. Garcia,1 M. Moya,1 F.D. Stone,4 P.J. Boston,5,6 M.L.N.E. Dapkevicius,7 and C. Riquelme7
1Biology Department, University of New Mexico, Albuquerque, New Mexico, USA.
2Geology Department, Western Illinois University, Macomb, Illinois, USA.
3Institute of Meteoritics, University of New Mexico, Albuquerque, New Mexico, USA.
4University of Hawai‘i at Hilo, Hilo, Hawai‘i, and Bishop Museum, Honolulu, Hawai‘i, USA.
5Earth and Environmental Sciences, New Mexico Institute of Mining and Technology, Socorro, New Mexico, USA.
6National Cave and Karst Research Institute, Carlsbad, New Mexico, USA.
7CITA-A, Departamento de Ciências Agrárias, Universidade dos Açores, Açores, Portugal.
corresponding authorCorresponding author.
Address correspondence to: D.E. Northup, Biology Department, MSC03 2020, University of New Mexico, Albuquerque, NM 87131, USA. E-mail:dnorthup/at/unm.edu
Received October 15, 2010; Accepted April 3, 2011.
Abstract
Lava caves contain a wealth of yellow, white, pink, tan, and gold-colored microbial mats; but in addition to these clearly biological mats, there are many secondary mineral deposits that are nonbiological in appearance. Secondary mineral deposits examined include an amorphous copper-silicate deposit (Hawai‘i) that is blue-green in color and contains reticulated and fuzzy filament morphologies. In the Azores, lava tubes contain iron-oxide formations, a soft ooze-like coating, and pink hexagons on basaltic glass, while gold-colored deposits are found in lava caves in New Mexico and Hawai‘i. A combination of scanning electron microscopy (SEM) and molecular techniques was used to analyze these communities. Molecular analyses of the microbial mats and secondary mineral deposits revealed a community that contains 14 phyla of bacteria across three locations: the Azores, New Mexico, and Hawai‘i. Similarities exist between bacterial phyla found in microbial mats and secondary minerals, but marked differences also occur, such as the lack of Actinobacteria in two-thirds of the secondary mineral deposits. The discovery that such deposits contain abundant life can help guide our detection of life on extraterrestrial bodies. Key Words: Biosignatures—Astrobiology—Bacteria—Caves—Life detection—Microbial mats. Astrobiology 11, 601–618.
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