Molecular Mechanism of Bacterial Attachment to Fe(III)-Oxide Surfaces

To date, our studies have concentrated upon two aspects of the chemistry and architecture of the Shewanella outer membrane surface: the influence of terminal electron acceptor during anaerobic respiration, and the role that protein secretion systems play in determining the presence and chemistry of exopolymers. Using Shewanella oneidensis strain MR-1 and S. putrefaciens strain 200R as model organisms we have developed a microelectrophoresis approach to estimating cell mobility in solution over a range of ionic strengths. From this data, and applying Ohshima's soft particle theory, we have successfully estimated the net electrostatic charge and relative thickness of any capsular material of the two model strains under various terminal electron acceptor availabilities. Additionally, by employing state-of-the-art cryo-electron microscopy techniques we have been able to not only confirm presence or absence of capsular material but also visualize the outer cell surface architecture in a completely hydrated state