Prokaryotic Diversity of Biological Soil Crusts in Aridlands of North America

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A grant has been awarded to Drs. Ferran Garcia-Pichel and Jean M. Schmidt at Arizona State University, in collaboration with Dr. Richard M. Keller at NASA Ames Research Center to conduct a survey of the microbial diversity present in biological soil crusts of North America. In arid lands, where plant cover is restricted, a half-inch thick live mantle of microbes develops in the topsoil that traps soil particles together and enriches the soils with organic carbon and nitrogen. Known as biological desert crusts, they cover spaces between plants, stabilizing the soil against wind erosion and preventing formation of blow-sands. There is presently a lack of knowledge regarding the microbial species inhabiting these important and widespread topsoil habitats. In a variety of sites of North American deserts and semi-deserts, the investigators will embark in an effort to detect and document local bacteria important in terms of abundance or novelty. For this, they will use modern DNA technology. They will also attempt to cultivate those microbes in the laboratory. Two repositories will be established. A DNA database will enable the future recognition of crust microbes by other investigators. Cultivated bacteria will be characterized with respect to their ecological role and properties, and will be deposited in public culture collections for the benefit of the scientific and biotechnology community at large. It is expected that these documentation and repositories will constitute the base for improved knowledge of desert bacterial communities, complementing our understanding of desert ecology, facilitating sound rangeland management, and enabling bioremediation attempts in heavily impacted arid areas.