Abstract
The distribution and function of microorganisms are vital issues in microbial ecology. The U. S. Department of Energy's Program, "Microbiology of the Deep Subsurface", concentrates on establishing fundamental scientific information about organisms at depth, and the use of these organisms for remediation of contaminants in deep vadose zone and groundwater environments. This investigation effectively extends the Biosphere hundreds of meters into the Geosphere and has direct implications for a variety of subsurface activities including bioremediation strategies.