Our research is primarily focused on the transmission and evolution of two zoonotic pathogens, enterohemorrhagic Escherichia coli (EHEC) and Salmonella . These pathogens reside in the intestinal tracts of animal hosts where they encounter diverse microbial communities, fluctuating nutrient levels, and myriad host factors. Transmission between hosts requires these pathogens to survive varied environmental conditions. The general stress protection system (regulated by the alternative sigma factor, σs) is known to play a central role in environmental persistence and transmission. Acid and desiccation tolerance are two transmission-associated phenotypes that are dependent upon σs –regulated genes. We are also investigating the impact of lysogenic bacteriophage genes on environmental persistence. EHEC harbor multiple lambda-like lysogens and cryptic phage remnants in their genome that facilitate genomic rearrangements, gene duplications, and deletions by homologous recombination. We are investigating how these phage-mediated genomic rearrangements influence the fitness of EHEC in its bovine host and the environment. The goals of our research are use results from these fundamental studies in the development of strategies to reduce pathogen transmission.

• Microbiology 303:Biology of Microorganisms

• Food Research Institute
• Professor, Department of Animal Sciences

• Molecular and Environmental Toxicology Center