Dr. David Smith

Associate Professor
Undergraduate Program Director

Contact

Smith

Office: 237 Wolf Hall

Mailing address:
Dept. of Biological Sciences
Wolf Hall
University of Delaware
Newark, DE 19716

Phone: (302) 831-2275
Fax: (302) 831-2281
E-mail: dwsmith@udel.edu

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Education

B.A.: University of California - San Diego
M.A.: Indiana University
Ph.D.: University of Wisconsin
Postdoctoral: University of California - Los Angeles

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Research Interests

• 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.

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Teaching

• 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

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Selected Publications

Williamson, Kurt E., Jennifer B. Schnitker, Mark Radosevich, David W. Smith, and K. Eric Wommack. 2008. Methodological framework for determination of lysogeny within soil bacterial isolates. Microbial Ecol. In Press.

Williamson, Kurt E., Mark Radosevich, David W. Smith, and K. Eric Wommack. 2007. Incidence of lysogeny within temperate and extreme soil environments. Environ. Microbiol. 9(10): 2563-2574.

Edgcomb, Virginia P., John H. McDonald, Richard Devereux, and David W. Smith. 1999. Estimation of Bacterial Cell numbers in humic Acid-Rich Salt Marsh Sediments with Probes Directed to 16s Ribosomal DNA. Applied and Environ. Micriobiol. 65: 1516-1523.

Smith, David W. 1992. Ecology of Sulfate-Reducing Bacteria. In: Sulfate- Reducing Bacteria: A Contemporary Perspective, J. Martin Odom and Rivers Singleton, Jr. Chapter 7. Science Tech Publishers.

Smith, David W. and William R. Strohl. 1990. Sulfur-Oxidizing Bacteria. In: Variations in Autotrophic Life, J. Shively and L. Barton, eds. Chapter 5. pp. 121-146. Academic Press.

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