Microbial Community Comparisons as a Function of the Physical and Geochemical Conditions of Galápagos Island Fumaroles

Abstract

Microbial communities at six fumarole fields on Sierra Negra and Alcedo volcanoes in the Galápagos Islands were examined to test how extreme geochemical conditions affect microbial biodiversity. The geologic substrates consist of basalt and rhyolite with varying amounts of alteration and sulfur precipitates. Collected samples of substrates varied in pH from 0–6, and substrate temperatures were within the mesophilic, thermophilic, and hyperthermophilic temperature ranges. Terminal restriction fragment length polymorphism (T-RFLP) analyses were done to assess the relationship of communities to each other as a function of geologic substrate, pH, and temperature. Comparative analyses of community diversity define two distinct clusters showing that the relationship between spatially separated microbial communities at the fumaroles is most influenced by the pH of the local environment.

Keywords:

• microbial communities
• fumaroles
• geochemistry
• pH

ACKNOWLEDGEMENTS

This work was funded by the National Geographic Society, grant number 7876-05, Sigma Xi, and NSF grant 0207605. We thank Dr. Larry Forney for the use of his laboratory for T-RFLP analyses and Dr. Ron Crawford for the use of his laboratory for DGGE analyses. Gilberto Flores, Nick Benardini, Carrie Jung, and Ursel Schuette contributed to this work and we thank them for their help. Thanks also to Dr. Tobias Fischer at the University of New Mexico for his guidance in completing the gas sampling and for the use of his laboratory to complete the gas analyses, Dr. Tom Williams at the University of Idaho for help with the SEM-EDS and to Jennifer Hinds for help with figures. The work could not have been accomplished without the support of the Charles Darwin Research Station and the permission of the Galápagos National Park.