University of maryland biotechnology institute desiccation and radiation tolerance by the anaerobic methane producing archaeon methanosarcina barkeri: a model for extraterrestrial adaptation the…

University of maryland biotechnology institute desiccation and radiation tolerance by the anaerobic methane producing archaeon methanosarcina barkeri: a model for extraterrestrial adaptation the discovery of microbial life in extremes ranging from deep submarine vents and subsurface rock to frozen antarctic lakes have extended parameters of environments now considered hospitable to life. Compared with most extremophiles that have evolved specific adaptations for survival within a narrow range of environments, the methanogenic archaeon m. Barkeri has the ability to survive in a broader 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 as an energy source for growth. Our preliminary data 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 ulticellular 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. We propose to study the mechanisms of adaptation by m. Barkeri to extreme conditions using biochemical, genomic and genetic approaches. DNA microarrays will be used to identify genes expressed in response to desiccation and compared with morphological changes observed by 3D tomography. By defining the adaptive strategies of m. Barkeri this research 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.