1. Department of Oral Biology, University of Florida, Gainesville, Florida; Department of Microbiology and Immunology, New York Medical College, Valhalla, New York 10595; Western Dairy Center and Department of Nutrition and Food Sciences, Utah State University, Logan, Utah; and Laboratoire de Microbiologie et Génétique Moléculaires, UMR 5100 CNRS-Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 9, France