Extremeophiles and Extreme Environments: November 2008

Jennifer Eigenbrode: Ice is a cryogenic vault for preserving organics and other materials that may record planetary processes. On Earth, cold temperatures retard against hydrolysis and oxidation, which degrade biomolecules and other organics, allowing traces of life to persist in the presence of impurities. We are exploring the dilute biological and organic inventory contained within modern glacial ice on Earth in order to understand the habitat of microorganisms in near-surface glacial ice and to distinguish allochthonous from autochthonous organic records.

Starting January 1, 2009, a new 4-year program will investigate hydrothermal systems on the Mid-Cayman Spreading Center (MCSC) under NASA's ASTEP program - a joint collaboration between Woods Hole Oceanographic Institution (WHOI), NASA's Jet Propulsion Laboratory (JPL), the Marine Biological Laboratory (MBL) and Duke University Marine Laboratory (DUML). The results of the work will be used to plan astrobiological exploration of any planetary body that can host hydrothermal circulation (for example, Europa).

Damhnait Gleeson: Borup Fiord Pass, located on the Canadian Arctic Island of Ellesmere, represents the only known site on Earth where sulfur minerals and glacial ice are found in intimate association. Spring waters access the surface of the ice during the melt season each year, depositing elemental sulfur, gypsum and calcite and exsolving H2S. The sulfur signature of the spring deposits is extensive enough to be detected and monitored from orbital satellite observations and an autonomous onboard classifier can provide temporal coverage of spring activity. Diverse microbial communities are active within the deposits and are mediating the geochemistry of the deposits by the sulfur redox transformations from which they gain energy. Cultivation experiments targeting sulfide-oxidizing members of the microbial community have isolated microorganisms from the spring deposits which are producing biomineralized sulfur structures in culture.

An ecosystem discovered 2.8 kilometers underground in the Mponeng Gold Mine near Johannesburg, South Africa two years ago has now been shown to comprise only a single species of microbe, existing on energy from radioactivity, completely independently of the Sun. The community of rod-shaped bacteria of the species Desulforudis audaxviator was discovered in 2005-06 by members of the NAI's Indiana-Princeton-Tennessee Astrobiology Initiative (IPTAI) Team. Their current results are presented in the October 10th issue of Science.