Flagellar motility is required for some enteric pathogens to colonize the intestine. Understanding how these pathogens overcome the mucus layer protecting the epithelial tissue is necessary for disease prevention. In this thesis project I examined bacterial motility in mucus to understand factors that facilitate mucus penetration and contrasted this with the motility in different visco-elastic materials.In this thesis, I used single cell tracking to characterize the flagellar motility of Vibrio cholerae and Salmonella enterica in different visco-elastic environments. First, I tested if V. cholerae and S. enterica were still motile in unprocessed pig intestinal mucus. Second, I studied factors that supported their motility in mucus. The first factor I investigated was the effect of pH on V. cholerae motility. I also studied the role of curvature in V. cholerae motility within mucus and some other visco-elastic environments, including liquid and agar. Last, I began investigation of the role of flagellar number in S. enterica motility. In these studies, I focused on analyzing the effective diffusion of bacteria and factors promoting the diffusion in each environment. My findings demonstrate that V. cholerae and S. enterica are able to swim in mucus, and that the torque, and the curvature of V. cholerae, and the flagellar number of S. enterica, play a significant role in bacteria motility in mucus and liquid. Moreover, my findings help elucidate the significance of motility in pathogenesis.
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