1. Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, P.O. Box 647040, and School of Molecular Biosciences, P.O. Box 644234, Washington State University, Pullman, Washington 99164; Division of Gastroenterology and Nutrition, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, Campus Box 8208, 660 South Euclid Avenue, St. Louis, Missouri 63110; Microbial Evolution Laboratory, National Food Safety and Toxicology Center, Michigan State...