2008 Annual Science Report
Indiana University, Bloomington Reporting | JUL 2007 – JUN 2008
Environmental Genomics Reveals a Single Species Ecosystem Deep Within the Earth.
The first metagenome sequence from a deep subsurface environment of South Africa has not only described the genetic composition of a new genera/species of sulfate reducing bacteria, Desulforudis Audaxviator, but has also revealed that it is by far the most dominant and most likely the sole resident of its environment. A single species ecosystem has never been reported before and runs counter to the prevalent concept that microorganisms live and evolve as communities of mixed species. Whether this bacterial species occurs in other deep subsurface environments around the world or whether other deep subsurface environments are also occupied by single species remains to be determined.
Environmental genomics reveals a single species ecosystem deep within the Earth.
A manuscript describing the metagenome of Desulforudis Audaxviator was sent to Science where it was accepted for review. In response to a request by one reviewer, CARD-FISH and SEM analyses were performed on some stored water samples from the same suite of samples that was the source of the metagenomic DNA in order to verify that the cells were actually cells and not spores and that the cells were Desulforudis Audaxviator. New data was incorporated into the manuscript. After a second review, the manuscript was returned with additional reviewer questions regarding the FISH technique and interpretation of the trace species with respect to the “rare biosphere” hypothesis. These second-round questions have been addressed and the manuscript has been sent back to the editor for what we hope is the final step toward acceptance for publication.
Several additional manuscripts on deep-subsurface microorganisms from gold mines in South Africa are accepted for publication or are in review. These papers describe microbially-mediated sulfur and methane cycling in a dolomite aquifer, an anaerobic biofilm from a deep borehole, and microorganisms associated with a deep mafic sill. All of these papers derive from field campaigns in previous years.
PROJECT INVESTIGATORS:Dylan Chivian
Project InvestigatorTerry Hazen
Project InvestigatorTullis Onstott
Project InvestigatorThomas Gihring
RELATED OBJECTIVES:Objective 2.1
Environment-dependent, molecular evolution in microorganisms
Co-evolution of microbial communities
Biochemical adaptation to extreme environments
Adaptation and evolution of life beyond Earth