Faculty Profile

Barbara B. Hemmingsen Professor, SDSU Scripps Institution of Oceanography, UCSD Ph.D., University of California San Diego Department of Biology, SDSU Molecular Biology Master’s Program Molecular Biology Institute (619) 594-6275 Email – bhemmingsen@sunstroke.sdsu.edu Microbial Ecology of Bioremediation of Petroleum Contaminated Soil, Fresh Water and Seawater   Hydrocarbon-degrading bacteria are present in low numbers in unpolluted environments.  Ideally, these populations would increase in number when petroleum hydrocarbons enter natural habitats.  This is usually prevented by the scarcity of some key nutrient: fixed nitrogen, phosphate, electron acceptor (oxygen or nitrate), water.  Humans attempt to clean up these polluted sites by relieving the nutrient deficiency or deficiencies; this environmentally friendly process is known as bioremediation.   Although it is generally accepted that biore-mediation can, with time, effect a mineralization of the hydrocarbons to innocuous carbon dioxide and water, very little is known about the specific bacteria involved, how their populations change during the process, and the best way to stimulate their growth and activity.  The research projects in Dr. Hemmingsen's laboratory use classical bacteriological and molecular tools to study these aspects of bioremediation in soil, in freshwater and in marine environments.   REPRESENTATIVE PUBLICATIONS   Bogardt, A. H., and B .B. Hemmingsen, Enumeration of phenanthrenedegrading bacteria by an overlayer technique: Use in the evaluation of petroleum contaminated sites, Appl. Env. Microbiol. 58:  25792582 (1992). Hemmingsen, B.B.  Use of exogenously grown bacteria for the clean up of contaminated soil and water.  Pp. 67-77 in G. Sundnes (ed.):  Human Impact on Selfrecruiting Populations.  Third International Kongsvoll Symposium.  Tapir Press, Trondheim, Norway.  (1993) Randall, J.D. and B.B. Hemmingsen, Evaluation of mineral agar plates for the enumeration of hydrocarbondegrading bacteria.  J. Microbiol. Methods 20: 103-113 (1994). Gersberg, R., K. G. Korth, L. E. Rice, J. D. Randall, A. H. Bogardt, J. W. Dawsey, and B.B. Hemmingsen, Chemical and microbial evaluation of in situ bioremediation of hydrocarbons in anoxic groundwater enriched with nutrients and nitrate. World J. Microbiol. Biotech. 11: 549-558 (1995). Rice, L. E. and B. B. Hemmingsen.  The enumeration of hydrocarbon-degrading bacteria. (1997) Invited chapter in D. Sheehan (ed.) Methods in Molecular Biotechnology: Protocols in Bioremediation,  pp. 99-109. The Humana Press, Totowa, NJ. Apitz, S.E., E. Arias, S.A. Clawson, E.W. Lin, R.J. Melcher, and B. B. Hemmingsen (1999) The development of a sterile, PAH-spiked, aged marine sediment for biodegradation experiments: preliminary chemical results. Organic Geochemistry, in press. Randall, J.D., and B. B. Hemmingsen, Microbial population changes in gasoline contaminated aquifers. (In preparation). Scripps Institution of Oceanography, UCSD Department of Biology San Diego State University 5500 Campanile Drive San Diego, CA 92182-4614 (619) 594-6275 Email - bhemming@sunstroke.sdsu.edu