Melissa A. Beckman is a Ph.D. graduate student in the Genome Science and Technology program in the Biology Division at the University of Tennessee, Knoxville.

Enteroaggregative Escherichi coli (EAEC) is an emerging pathogen associated with diarrheal illness in humans worldwide. A highly conserved, highly prevalent, and immunogenic cell surface protein of EAEC strains is dispersin. It has been proposed that dispersin imparts a positive charge to the bacterial cell surface allowing the bacteria to efficiently penetrate and colonize multiple foci on the negatively charged intestinal mucosa. Physical properties of the bacterial cell surface, such as rigidity, may be influenced by the presence of dispersin and may contribute to pathogenicity. Using the system developed in our laboratory for mounting and imaging bacterial cells by atomic force microscopy (AFM), in liquid, on gelatin coated mica surfaces, we are measuring cell surface elasticity of the live wild type and the dispersin deletion mutant of EAEC strain 042.