Stephenson

Thermoacidophiles in low pH environments: the connection between deep-sea vent systems and terrestrial sites

S.K. Stephenson¹*, K.L. Rogers¹, B.M. Hynek²’³, & T.M. McCollom²

Corresponding author: sksr5b@mizzou.edu
¹University of Missouri, Department of Geological Sciences, Columbia, MO, 65211
²University of Colorado, Laboratory for Atmospheric and Space Physics, Boulder, CO, 80309
³University of Colorado, Department of Geological Sciences, Boulder, CO, 80309

Abstract:
Thermophiles with diverse metabolic strategies inhabit both terrestrial and marine hydrothermal systems, including many that exhibit extreme acidic and alkaline conditions. The hot (40 to 400° C) and acidic (pH 1-5) fumaroles of Cerro Negro volcano, Nicaragua, are an ideal terrestrial analog to acidic deep-sea vent systems and could serve to extend the known habitats of thermoacidophiles. We are investigating geochemical habitats at Cerro Negro, particularly focusing on the amount of energy available to the microbial community involved in acidic thermal alteration. Novel thermophilic organisms, particularly thermoacidophiles, are being targeted for cultivation under the in situ conditions (pH, temperature, and geochemical composition) as measured at Cerro Negro, in order to expand our understanding of their metabolic, physiologic, and environmental diversity. Additionally, we are applying molecular techniques to elucidate the diversity of thermophiles that inhabit the acidic thermal environments at Cerro Negro. Identifying the viability of thermoacidophiles in a terrestrial fumarole environment will help to illuminate possible metabolisms of microorganisms in similar hydrothermal acidic environments, including deep-sea vent systems.

Contributions to Integration and Synthesis:
Deep-sea vent systems encompass a wide range of geochemical environments, including those that exhibit extremes in pH, energy availability, and nutrient supply. They also host a diverse group of microorganisms, many of which are only known through their DNA sequences. Recently, a cultivated representative of the DHVE group, Aciduliprofundum boonei, helped to identify this group as thermoacidophiles (Reysenbach et al., 2006). While this group has been identified through gene sequences throughout deep-sea vent systems, little is known about the extent of their habitats. Identifying additional thermophiles at Cerro Negro can provide a greater understanding of the types of low pH environments where additional thermoacidophiles may thrive in deep-sea vent systems, including the Lau Basin ISS (pH as low as 2) (Fouquet et al., 1993), as well as the Rainbow Hydrothermal Field (pH=3-4) (Konn et al., 2009).

References:
Fouquet, Y., von Stackelburg, U., Charlou, J.L., Erzinger, J., Herzig, P.M., Muhe, R., Wiedicke, M., 1993, Metallogenesis in back-arc environments: The Lau Basin example, Economic Geology, vol. 88, p. 2154-81.
Konn, C., Charlou, J.L., Donval, J.P., Holm, N.G., Dehairs F., Bouillon, S., 2009, Hydrocarbons and oxidized organic compounds in hydrothermal fluids from Rainbow and Lost City ultramafic-hosted vents, Chemical Geology, vol. 258, p. 299-314.
Reysenbach, A., Liu, Y., Banta, A.B., Beveridge, T.J., Kirshtein, J.D., Schouten, S., Tivey, M.K., Von Damm, K.L., Voytek, M.A., 2006, A ubiquitous thermoacidophilic archaeon from deep-sea hydrothermal vents, Nature, vol. 442, no. 27, p. 444-7.