|
Biology of Methanogenesis |
Department of Marine Biotechnology UMBC - Institute of Marine & Environmental Technology
Astrobiology: Defining the Limits of Life
The discovery of
microbial life in extremes ranging from deep submarine hypothermal vents and
subsurface rock to the frozen lakes of Antarctica have extended parameters of
extraterrestrial environments that we now consider hospitable to life.
Compared with most extremophiles that have evolved adaptations for growth
within a narrow range of environments, the methanogenic archaeon M. barkeri
has the ability to adapt to a broad range of “adverse” environments. This
obligately anaerobic, single cell microorganism requires only water and
minerals as nutrients can obtain cellular nitrogen from nitrogen gas and uses
simple substrates such as hydrogen and carbon dioxide an energy source for
growth. Our preliminary data below indicate that M. barkeri has
developed mechanisms that enable this species to survive extreme conditions
similar to those observed for spore formers, but with unique mechanisms that
do not involve spore formation, nor does this species depend on robust DNA
repair mechanisms associated with hyperthermophiles and halophiles for long
term survival in a desiccated state. The formation of multicellular structures
by synthesis of a unique extracellular polymeric substance (EPS), which is
chemically similar to mammalian chondroitin, has a key role in the long term
survival of this species in a desiccated state without significant loss of
viability. Unknown processes associated with the desiccation process also
appear to increase resistance of desiccated cells to high temperatures and
oxidation. In this project we are studying the mechanisms of adaptation by M. barkeri
to extreme conditions using biochemical, genomic and genetic approaches.
In addition to its unique physiology and adaptive abilities, M. barkeri
is well poised for research with the recent completion of its genome sequence
and the availability of a genetic system. DNA microarrays are used to
identify genes expressed in response to desiccation and compared with
morphological changes observed by 3D tomography. This project addresses the
goal of NASA's Exobiology and Evolutionary Biology Program to understand the
origin, evolution, distribution, and future of life in the Universe,
specifically the potential of life to adapt to different environments, and the
implications for life elsewhere.
By defining the
adaptive strategies of M. barkeri the project will seek to
redefine the range of physiological parameters for survival and identify on a
molecular level the unique mechanisms that enable this species to maintain
viability after extended periods of desiccation.
Collaborators
Drs. Norman Pace and Chuck Robertson,
University of Colorado-Boulder
Project Team
Kimberly Anderson,
Ph.D.
Related Publications and Abstracts
Anderson, K. and K.R. Sowers. 2012. Desiccation as a Long-Term Survival Mechanism for the archaeon Methanosarcina barkeri. Appl. Environ. Microbiol. 78: 1473-1479. [ABSTRACT]
I.N. Reid, W.B. Sparks, S. Lubow, M. McGrath, M. Livio, J. Valenti, K.R. Sowers, H.D. Shukla, S. MacAuley, T. Miller, R. Suvanasuthi, R. Belas, A. Colman, F.T. Robb, P. DasSarma, J.A. Müller, J.A. Coker, R. Cavicchioli, F. Chen, S. DasSarma. 2006. Terrestrial models for extraterrestrial life: methanogens and halophiles at Martian temperatures. Int. J. Astrobiol. 5: 89-97. [ABSTRACT]
Maeder, D.L., I. Anderson, T. Brettin, D. Bruce, P. Gilna, C. S. Han, A. Lapidus, W.W. Metcalf, E. Saunders, R. Tapia, and K.R. Sowers. 2006. The Methanosarcina barkeri genome: comparative analysis with Methanosarcina acetivorans and Methanosarcina mazei reveals extensive rearrangement within methanosarcinal genomes. J. Bacteriol. 188: 7922-7931. [ABSTRACT]
Sowers, K.R. Antarctic Extremophiles and Extraterrestrial Life. Astrobiology Afternoon, Space Telescope Science Institute, Baltimore, MD. Jan 20, 2005
Saunders, Neil F.W., T. Thomas, P.M.G. Curmi, J. Mattick, E. Kuczek, R. Slade, J. Davis, P. Franzmann, D. Boone, K. Rusterholtz, R. Feldman, C. Gates, S. Bench, K. Sowers, K. Kadner, A. Aerts, P. Dehal, C. Detter, T. Glavina, S. Lucas, F. Larimer, L. Hauser, M. Land and R. Cavicchioli. 2003. Mechanisms of Thermal adaptation revealed by the genomes of the Antarctic Archaea, Methanogenium frigidum and Methanococcoides burtonii. Gen. Res. 13: 1580-1588.
Galagan, J.E., et al. 2002. The genome of Methanosarcina acetivorans reveals extensive metabolic and physiological diversity. Gen. Res. 12: 532-542.
Funded by
