Microorganisms have inhabited the Earth for 3.4 billion years of its history. They are essential for the evolution of its minerals, its major geochemical cycles, and its atmosphere, yet the extent of their diversity, their metabolic capabilities, and their ecosystem-level interactions remains vastly unexplored.

Understanding the link between the geochemistry we observe and the large-scale impact of microbial activity is critical if we want to learn more about our own biosphere, and how to better conserve and protect the environment. We study microorganisms that live in extreme environments, such as hypersaline environments and extremely dry deserts, because under those extreme conditions - where the impact on cellular components is intense - microorganisms have evolved robust adaptive mechanisms.

Our work focuses on processes that allow microorganisms to adapt to their environments and to changing environmental conditions. We are particularly interested in mechanisms of resistance to oxidative stress, desiccation, and radiation. We use a combination of genomic and genetic methods to identify proteins involved in the repair of DNA damage in the Archaea and to elucidate the regulatory networks underlying the stress response to cellular damage.

At the ecosystem level, we study the genetic and functional diversity of microbial communities from extreme environments to identify the mechanisms that sustain biodiversity and ecosystem functioning. Our field sites include the Atacama Desert, Chile, and the Dry Valleys of Antarctica, both extremely dry areas and Earth analogs for Martian environments.

Our research is directly related to Astrobiology. Visit the Institute for Planets and Life web site at the Space Telescope Science Institute and Johns Hopkins University

Atacama Desert, Chile

Crits-Christoph, A., C. K. Robinson, B. Ma, J. Ravel, J. Wierzchos, C. Ascaso, O. Artieda, V. Souza-Egipsy, C. Casero, and J. DiRuggiero. 2016. Phylogenetic and functional substrate specificity for endolithic microbial communities in hyper-arid environments. Frontiers Microbiol. http://dx.doi.org/10.3389/fmicb.2016.00301

Crits-Christoph, A. D. R. Gelsinger, B. Ma, J. Wierzchos, J. Ravel, A. F. Davila, M. C. Casero, and J. DiRuggiero. 2016. Functional interactions of archaea, bacteria and viruses in a hypersaline endolithic community. Env. Microbiol. DOI: 10.1111/1462-2920.13259

Goordial, J, A. Davila, D. Lacelle, W. Pollard, M.M Marinova, C.W. Greer, J. DiRuggiero, C.P. McKay and L.G. Whyte. 2015. Nearing the cold-arid limits of microbial life in permafrost of an upper dry valley, Antarctica. ISMEJ in press.

Davila, A.F., I. Hawes, J. Garcia, D.R. Gelsinger. J. DiRuggiero, C. Ascaso, A. Osano, and J. Wierzchos. 2015. In situ metabolism in halite endolithic microbial communities of the hyperarid Atacama Desert. Frontiers Microbiol. 6:1035. http://dx.doi.org/10.3389/fmicb.2015.01035

Wierzchos, J., J. DiRuggiero, P. Vítek, O. Artieda, V. Souza-Egipsy, P. Skaloud, M. Tisza, A. F. Davila, C. Vílchez, I. Garbayo, and C. Ascaso. 2015. Adaptation strategies of endolithic chlorophototrophs to survive the hyperarid and extreme solar radiation environment of the Atacama Desert. Frontiers Microbiol. 6: 934. http://dx.doi.org/10.3389/fmicb.2015.00934

Robinson, C. K., J. Wierzchos, C. Black, A. Crits-Christoph, B. Ma, J. Ravel, C. Ascaso, O. Artieda, S. Valea, M. Roldan, B. Gomez-Silva, and J. DiRuggiero. 2015. Microbial diversity and the presence of algae in halite endolithic communities are correlated to atmospheric moisture in the hyper-arid zone of the Atacama Desert. Environ Microbiol doi: 17: 299-315

Crits-Christoph, A., C. K. Robinson, T. Barnum, J. Ravel, F. Fricke, A. Davila, B. Jedynak, C.P. McKay, and J. DiRuggiero. 2013. Colonization patterns of soil microbial communities in the Atacama Desert. Microbiome 1:28.

DiRuggiero, J., J. Wierzchos, C. K. Robinson, T. Souterre, R. Ravel, O. Artieda, V. Souza- Egipsy, and C. Ascaso. 2013. Microbial colonization of chasmoendolithic habitats in the hyper-arid zone of the Atacama Desert. Biogeosciences 10:2439-2450

Webb, K., J. Wu, C.K. Robinson, N. Tomiya, Y. Lee, and J. DiRuggiero. 2013. Effects of intracellular Mn on the radiation resistance of the halophilic archaeon Halobacterium salinarum. Extremophiles. 17: 485-497

Webb, K.M., and J. DiRuggiero. 2012. Role of Mn2+ and compatible solutes in the radiation resistance of thermophilic bacteria and archaea. Archaea. 2012:Article ID 845756. doi:10.1155/2012/845756

Robinson, C.K., K.M. Webb, A. Kaur, P. Jaruga, M. Dizdaroglu, N. Baliga, A. Place, and J. DiRuggiero. 2011. A major role for non-enzymatic antioxidant processes in the radioresistance of Halobacterium salinarum. J. Bacteriol. 193:1653-1662

Kaur, A., P.T. Van, C.R. Busch, C. Robinson, M. Pan, W.L. Pang, D. Reiss, J. DiRuggiero, and N.S. Baliga. 2010. Coordination of frontline defense mechanisms under severe oxidative stress. Mol. Syst. Biol. 393 doi:10.1038/msb.2010.50

Kish, A., G. Kirkali, C. Robinson, R. Rosenblatt, P. Jaruga, M. Dizdaroglu, and J. DiRuggiero. 2009. Salt shield: intracellular salts provide protection against ionizing radiation in the halophilic archaeon, Halobacterium salinarum NRC-1 Environ. Microbiol. 11:1066-1078.

Graduate Students

Diego Gelsinger
Kevin Maciuba

Research Technologist

Jeremiah Miller

Undergraduate Students

Alex Crits-Christoph
Philip Lin