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David Smith, Ph.D.
- BISC 300 - Introduction to Microbiology
- BISC 403 - Genetic and Evolutionary Biology
- BISC 641* - Microbial Ecology
- BISC 645* - Bacterial Evolution
- MALS 619 - The Scientist in Society
- MALS 620 - The Use of Science in Public Discourse
*Course web site available through MyCourses
- Microbial Ecology - I have investigated the bacterial activities of the sulfur and nitrogen cycles in the Canary Creek salt marsh in Lewes, Delaware. Emphasis has been on the dynamics of these processes and the potential metabolic rates which can be realized in response to controlled alterations of the environment in small samples. A major interest has been the response of these organisms and activities to changes in salinity, a presumably important controlling factor in this estuarine habitat. We have demonstrated, rather surprisingly, that many of the bacteria in these marshes are not well-adapted to the salinities they normally experience. Work is continuing to elucidate a mechanistic explanation of this apparent maladaptation.
- Bacterial Physiology - Several physiological studies are extensions of results from the above-mentioned ecological measurements. Physiological interactions between different bacterial types have been actively studied in many laboratories. One example which has received much attention is the complex synergistic/antagonistic relation between sulfate-reducing bacteria and methane-producing bacteria. We have demonstrated that a major analytical tool in these studies, the use of supposedly specific inhibitors, has unexpected complications.
- Bacterial Evolution - The interaction between physiology and ecology is at the heart of evolution, especially for microorganisms. A student in my laboratory investigated the so-called "directed evolution" phenomenon reported by Cairns in 1988 and elaborated by others including Barry Hall. Our approach has been to critically evaluate the microbiological procedures used so that the evolutionary conclusions are on a sounder footing. It appears that many of the previous claims need to be reevaluated in light of our results.
- Williamson KE, Schnitker JB, Radosevich M, Smith DW, Wommack KE. Cultivation-based assessment of lysogeny among soil bacteria. Microb Ecol. 2008;56(3):437–447.
- Williamson KE, Radosevich M, Smith DW, Wommack KE. Incidence of lysogeny within temperate and extreme soil environments. Environ Microbiol. 2007;9(10):2563–2574.
- Edgcomb VP, McDonald JH, Devereux R, Smith DW. Estimation of bacterial cell numbers in humic acid-rich salt marsh sediments with probes directed to 16S ribosomal DNA. Appl Environ Microbiol. 1999;65(4):1516–1523.
- Smith DW. Ecology of Sulfate-Reducing Bacteria. In: Odom JM, Singleton R, eds. Sulfate-Reducing Bacteria: A Contemporary Perspective. Science Tech Publishers; 1992.
- Smith DW, Strohl WR. Sulfur-Oxidizing Bacteria. In: Shively J, Barton L, eds. Variations in Autotrophic Life. Academic Press; 1990:121–146.
Phone: (302) 831-2275
Fax: (302) 831-2281
Office: 237 Wolf Hall
Department of Biological Sciences
University of Delaware
Newark, DE 19716
- B.A. - University of California, San Diego
- M.A. - Indiana University
- Ph.D. - University of Wisconsin
- Postdoctoral - University of California, Los Angeles