NASA Astrobiology Institute (NAI)

1. Molecular and Isotopic Microbial Community Analysis of Deep Subsurface Sediments

   Project Investigators: Mitchell Sogin, Andreas Teske

   Other Project Members

   Zena Cardman (Undergraduate Student)

   Christopher House (Collaborator)

   Susan Huse (Collaborator)

   Summary

   My research examines the microbial populations found in deeply buried marine sediments. By examining the presence of certain types of microorganisms by detecting their genetic signatures, we can start to understand who there microbes are and what they do. It appears that deep sediments contain highly unusual microorganisms and may defy some commonly-held notions about the diversity of species in an ecosystem.

   Astrobiology Roadmap Objectives:

   • Objective 5: Describe the sequences of causes and effects associated with the development of Earth's early biosphere and the global environment.
   • Objective 5: Describe the sequences of causes and effects associated with the development of Earth's early biosphere and the global environment.
   • Objective 5: Describe the sequences of causes and effects associated with the development of Earth's early biosphere and the global environment.
   • Objective 6: Define how ecophysiological processes structure microbial communities, influence their adaptation and evolution, and affect their detection on other planets.

   Project Progress

   In the past year, I have made significant progress towards my research goals. I completed a study of the “rare biosphere” of the deep sediment through tagged-sequencing and am preparing the data from this project into manuscripts.

   
   

   Bacterial and Archaeal Rarefecation Curves, Peru Margin samples. Sites sampled (depths): ODP 1229 (2,30,50,91 mbsf); ODP 1227 (7,35,58 mbsf). Data from J. Biddle, S. Huse and A. Teske 2008.

   
   

   Phylogenetic groups of all tagged sequences from Peru Margin samples. Data from J. Biddle, S. Huse and A. Teske 2008.

   Additionally, I am involved in 5 other projects, which include: examining the changes in a sediment microbial community during sample storage, investigating the diversity, abundance and isotopic signatures of microorganisms in a Beggiatoa mat from Guaymas Basin, developing new methods to detect subsurface groups of Archaea, determining genomic signatures of subsurface microbial groups through large fragment sequencing and examining low-biomass sediments of the open ocean for signs of life. The tagged-sequencing and sample storage projects have been presented to international audiences at scientific meetings. Additionally, I had a manuscript from last year’s work accepted for publication in PNAS.

   Mission Involvement

   Astrobiology Field Laboratory, future extraterrestrial landers, rovers

   My work examines a low-biomass environment, which is most likely still 1,000X more populated than the Martian subsurface. Findings from these experiments will guide future experiments to discover extraterrestrial life and interpret results from landers and rovers. I was part of the AFL science steering group.

   Cross-Team Collaborations

   Christopher House (PSARC, Penn State NAI): Chris and his student, Mandi Klingensmith, have been collaborators on the projects on deep sediment metagenomics and have also helped to study the open-ocean sediment sites.

   Steve D'Hondt (URI, former NAI): Steve is a collaborator on the tagged-sequencing work and was instrumental in securing the funding for this project from the Keck foundation.

Publications

Biddle, J.F., Fitz-Gibbon, S., Schuster, S.C., Brenchley, J.E. & House, C.H.  (2008).  Metagenomic signatures of the Peru Margin subseafloor biosphere show a genetically distinct environment.  Proc Natl Acad Sci U S A, 105(30):10583-8  [Online].

Biddle, J.F., Huse, S.M., Sogin, M.L. & Teske, A.  (2008).  Archaeal and bacterial diversity of deep marine subsurface sediments analysed by V6-tag sequencing.  Poster and Abstract at ICOMM Workshop "Assessing marine microbial diversity: problems and solutions".  Amsterdam, The Netherlands..

Biddle, J.F. & Teske, A.  (2008).  A genetic view of diversity beneath the seafloor.  18th Goldschmidt Conference.  Vancouver, BC, Canada.