Abstract of Dissertation Presented to the Graduate School
              of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy

     POLYHEDRAL ORGANELLES INVOLVED IN THE B12-DEPEDENDENT METABOLISM OF 1,2-PROPANEDIOL IN Salmonella enterica SEROVAR TYPHIMURIUM LT2

                                       By

                             Gregory Dale Havemann

                                   May 2003

Chair: Thomas A. Bobik
Major Department: Microbiology and Cell Science

     In an effort to better understand salmonella physiology and coenzyme B12dependent processes, Salmonella enterica has been used as a model to study coenzyme B12-dependent degradation of 1,2-propanediol. One of the most surprising findings was the observation of polyhedral organelles in S. enterica cells grown on propanediol. Although these organelles appeared similar to carboxysomes, which are involved in C02fixation in autotrophic bacteria, a similar function in S. enterica was unlikely since this organism is not an autotroph and does not fix CO2. This dissertation investigates the structure and function of these unusual bacterial organelles.

     The conditions required for organelle formation were defined, and a time course of organelle formation revealed that their synthesis correlated to a metabolic shift to growth on propanediol. In addition, two genes, pduA and pduB, were shown to be involved in organelle formation. To further investigate the role of the PduA protein in polyhedral organelle formation, the pduA gene was cloned and overexpressed. The protein product