LExEn: Molecular Diversity and Structure of Photoendolithic Ecosystems

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

DEB-0085490 Norman R. Pace Dr. Norman R. Pace of the University of Colorado at Boulder has been awarded a grant to study microbial diversity of a highly unusual, but perhaps fundamentally important environment, the endolithosphere. The "endolithic" habitat, comprised of the pore-space within rocks, is a ubiquitous extreme environment on Earth, and may contribute significantly to global biomass. Although of large significance to our understanding of microbial diversity and bio-geochemical processes, such as nutrient cycling and mineral weathering, relatively little is known about microbial constituents of endolithic ecosystems. This research project will survey, identify and study the microbial organisms that occur in selected photosynthesis-driven endolithic communities. Molecular DNA-sequence-based methods will be used that do not require pure-cultivation in order to identify organisms and to gain information about them. This consideration is crucial for such environmental analyses because most (>99%) microorganisms in environmental samples are not cultured using standard techniques. The specific goals of the proposed program are the following: i. To identify and quantify the constituents of selected temperate-zone (Colorado) endolithic communities, DNA sequences will be obtained from microorganisms in the environment, and analyzed using phylogenetic methods to explore their evolutionary relationship. The results will provide insight into the physiological workings of photoendolithic ecosystems, and expand our view of microbial diversity. ii. To validate organisms indicated by environmental sequences, community samples will be visualized by microscopy using fluorescent tags (probes) to these specific environmental DNA sequences. The results will disclose the morphological properties of organisms that correspond to the selected sequences and reveal their physical distribution in the community. iii. This survey will likely encounter novel organisms and raise questions about their properties. To explore such physiological hypotheses, DNA-based probes will be used to monitor the growth of selected organisms in culture. The results are expected to identify many new cultivatable microbes for subsequent culture-study, and will provide information regarding their metabolic capabilities. Overall, the proposed program is expected to advance substantially our understanding of the kinds and activities of organisms that comprise photosynthesis-based endolithic communities.