"Why do you think Earth and Venus have an atmosphere and Mercury has only trace gases, while Mars a very weak atmosphere?"
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Seminar Detail
Microbial and
Genomic Insights Into Microbial Life in Permafrost
Presenter: Jim Tiedje ()
July 28, 2003 12:00 AM Pacific
Permafrost is continuously frozen soil, sediment or bedrock and occupies
over 20% of Earth's land surface. Microbes that live in this environment
must survive subzero temperatures, low water activity, low energy and
resource availability, long-term exposure to gamma radiation and cell aging.
Several of these conditions appear to be similar to those on other astral
bodies making permafrost a useful model for studying microbial adaptation to
these stresses. Most of Earth's permafrost harbors at least some
prokaryotes that have retained viability over geological time periods and
when the temperature is raised increase or renew their physiological
activity. We examined microbial populations in both Arctic and Antarctic
permafrost by determining which microbes are detected in the permafrost DNA,
which are detected after the permafrost has been allowed to incubate a few
weeks at 10C and which are detected after isolation of viable cultures.
Arctic permafrost, some of which has been continuously frozen for up to 3-4
million years, has a relatively large microbial population while the
Antarctic has lesser numbers. Both permafrost DNA and culture approaches
detect high and low GC gram-positive bacteria and Proteobacteria, suggesting
that they are best adapted to this environment. Most of the isolates grow at
2.5C and have as their nearest phylogenetic relative other strains from
cold environments. These observations suggest that adaptation to these
conditions is a phylogenetically conserved trait. We have selected two
Arctic isolates from ancient permafrost for genome sequencing, a
Psychrobacter strain and an Exiguobacterium strain, representatives of two
of the three most common groups present. The Psychrobacter genome is now
(essentially) closed and the Exiguobacterium genome is approaching high
draft status. We have begun both the genomic and proteomic analysis via
comparative genomics, microarrays and proteomics, especially examining up
and down regulated genes and gene products in response to temperature and
salt stresses.
(Special acknowledgement to team members at MSU, The Joint Genome Institute
and Univ. of Michigan for the portion of the Center¹s work summarized in
this presentation.)Participation Instructions
http://nai.arc.nasa.gov/seminars/instructions.cfm
December 21, 2007
The Director’s Seminar series features talks from scientists who are invited by the NAI Director to present their research results to the community. A primary goal of the seminars is to encourage interdisciplinary collaboration across NAI teams and within the astrobiology community at large.
Team Overview Seminars describe the work of the fourteen NAI teams and NAI Central. They offer an opportunity to find out more about the science, E/PO and other activities being performed by the NAI teams and the NAI Central office.
The Forum for Astrobiology Research (FAR) provides an opportunity for graduate students to present their research results and to meet as a student community for networking and mutual support.
The University of Washington seminar series is hosted by the NAI Virtual Planetary Lab (VPL) team from the UW campus in Seattle.
