• Mechanisms of enzyme action
• microbial stress adaptation
• solute transport systems
• NMR
• dairy chemistry

EDUCATION:

1971   B.A., Biochemistry, University of California, Berkeley
1976   Ph.D., Chemistry, University of California, San Diego

POSITIONS HELD:

Postdoctoral Research Associate, University of Southern California, Los Angeles, 1977
Postdoctoral Trainee/Research Associate, The Institute of Cancer Research, Philadelphia, PA, 1977-81
Research Fellow in Chemistry, California Institute of Technology, Pasadena, CA, 1981-82
Professor and Chemist, Department of Food Science and Technology, UC Davis, Davis, California, 1982 Ð present
Director, UCD NMR Facility, 1996-present

RECENT SIGNIFICANT FINDINGS/ACCOMPLISHMENTS

We are examining the mechanism of adaptation to osmotic stress and to growth at low temperature by Listeria monocytogenes, a notable psychrotrophic food-borne pathogen. We found that part of the adaptation process to osmotic and to chill stress involves the accumulation of the "compatible solutes" glycine betaine and carnitine from the medium (i.e., the food which they contaminate). The accumulation of there solutes has been demonstrated in meat products and milk whey. We identified three transport systems for these solutes: glycine betaine porter I ( sodium-coupled glycine betaine symporter, the product of the betL gene), glycine betaine porter II (an ATP-linked glycine betaine transporter), and OpuC (an ATP-linked carnitine transporter). We have shown that glycine betaine porters I and II can be made to function in membrane vesicles. Glycine betaine porter I is activated by hyperosmotic stress, particularly that involving Na+ ion. Glycine betaine porter II and OpuC are activated by either hyperosmotic stress or by chill.

SELECTED PUBLICATIONS:

• Glycine betaine confers enhanced osmotolerance and cryotolerance in Listeria monocytogenes. R. Ko, L.T. Smith and G.M. Smith. 1994. Journal of Bacteriology 176:426-431.
• Food biochemistry: Food lipids, carbohydrates, and nucleic acids. G.M. Smith and J.R. Whitaker. 1994. IN: The Encyclopedia of Agricultural Sciences, Academic Press, San Diego, CA.
• Food biochemistry: Food proteins, enzymes and enzyme inhibitors. G.M. Smith and J.R. Whitaker. 1994. IN: The Encyclopedia of Agricultural Sciences, Academic Press, San Diego, CA.
• Food biochemistry: Food pigments, flavors, aromas, and stability. G.M. Smith and J.R. Whitaker. 1994. IN: The Encyclopedia of Agricultural Sciences, Academic Press, San Diego, CA.
• The prominent role of glucosylglycerol in osmotic regulation in Pseudomonas mendocina SKB70. L.T. Smith, J.-A. Pocard, G.M. Smith and D.L. Rudulier. 1994. Journal of Bacteriology 176:6877-6884.
• Stable isotope methods for the study of beta-carotene-d8 metabolism in humans utilizing tandem mass spectrometry and high-performance liquid chromatography. S.R. Dueker, A.D. Jones, G.M. Smith and A.J. Clifford. 1994. Analytical Chemistry 66:4177-4185.
• Studies of protein structure by NMR spectroscopy. G.M. Smith. 1995. Annual Reports on NMR Spectroscopy 31:171-218.
• The nature of enzymes. G.M. Smith. 1995. p.5-72. IN: Biotechnology, Vol. 9: Enzymes, Biomass, Food and Feed, VCH Publishers, New York.
• Role of glycine betaine and related osmolytes in osmotic stress adaptation in Yersinia enterocolitica ATCC 9610. S. Park, L.T. Smith and G.M. Smith. 1995. Applied and Environmental Microbiology 61(12):4378-4381.
• Sodium-driven, osmotically activated glycine betaine transport in Listeria monocytogenes membrane vesicles. P.N.M. Gerhardt, L.T. Smith and G.M. Smith. 1996. Journal of Bacteriology 178(22):6105-6109.
• Isolation and fatty acid analysis of neutral and polar lipids of the food bacterium Listeria monocytogenes. S. Mastronicolis, J.B. German and G.M. Smith. 1996. Food Chemistry 57(3):451-456. Thermal denaturation of b-lactoglobulin: A 1H study. J. Belloque and G.M. Smith. 1998. Journal of Agricultural and Food Chemistry 46(5):1805-1813.
• Influence of cold shock on the fatty-acid composition of different lipid classes of the food-borne pathogen Listeria monocytogenes. S.K. Mastronicolis, J.B. German, N. Megoulas, E. Petrou, P. Foka and G.M. Smith. 1998. Food Microbiology 15(3):299-306.
• Solute transport enzymes related to stress tolerance in Listeria monocytogenes: A review. G.M. Smith, L.T. Smith, P.N.M. Gerhardt and R. Ko. 1998. Journal of Food Biochemistry 22:269-285. Kinetic measurements of cellulase activity on insoluble substrates using disodium 2,2' bicinchoninate. D.B. Johnston, S.P. Shoemaker, G.M. Smith and J.R. Whitaker. 1998. Journal of Food Biochemistry 22:301-319.
• 1H-Nuclear magnetic resonance studies on the conformational changes related to the foaming properties of b-lactoglobulin. J. Belloque and G.M. Smith. 1998. Journal of Dairy Science 81(10):2580-2587.
• Whey proteins as neutraceuticals. G. Pasin and G.M. Smith. 1998. Recent Research Developments in Nutrition Research 2:177-185.
• Osmotic and chill activation of glycine betaine porter II in Listeria monocytogenes membrane vesicles. P.N.M. Gerhardt, L.T. Smith and G.M. Smith. 2000. Journal of Bacteriology 182(9):2544-2550.
• A 1H-NMR study of the effects of high pressure on b-lactoglobulin A, B, and AB. J. Belloque, R. Lopez-Fandino and G.M. Smith. 2000. Journal of Agricultural and Food Chemistry 48:3906-3912.
• Elevated carnitine accumulation by Listeria monocytogenes impaired in glycine betaine transport is insufficient to restore wild-type cryotolerance in milk whey. A.S. Angelidis, L.T. Smith and G.M. Smith. 2002. International Journal of Food Microbiology 75:1-9.
• Identification of OpuC as a chill-activated and osmotically activated carnitine transporter in Listeria monocytogenes. A.S. Angelidis, L.T. Smith, L.M. Hoffmann and G.M. Smith. 2002. Applied Environmental Microbiology 68. In press.