Submitted to: Biomacromolecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/30/2009
Publication Date: 9/14/2009
Publication URL: http://www.ars.usda.gov/SP2UserFiles/Place/53102000/pdf_pubs/P2286.pdf
Citation: Kim, H.N., Hong, Y., Lee, I., Bradford, S.A., Walker, S.L. 2009. Surface Characteristics and Adhesion Behavior of Escherichia coli O157:H7: Role of Extracellular Macromolecules. Biomacromolecules. 10(9):2556-2564. Interpretive Summary: The bacterium Escherichia coli O157:H7 is found in animal wastes, and that has been linked to water and fresh produce disease outbreaks. A detailed cell surface characterization study was initiated in this work to better understand properties of this bacterium that affect its fate in the environment. Results indicate surface molecules have a large influence on charge properties of E. coli O157:H7 that will affect interactions of these cells with solids, plants, and with other bacteria. This information should be of interest to scientists, engineers, and health professionals concerned with the fate of E. coli O157:H7 in the environment.
Technical Abstract: Surface macromolecule cleavage experiments were conducted on enterohaemorrhagic Escherichia coli O157:H7 cells to investigate the influence of these macromolecules on cell surface properties. Electrophoretic mobility, hydrophobicity, and titration experiments were carried out on proteinase K treated and untreated cells for this purpose. Differences in the surface characteristics of both cells were interpreted using soft particle theory. Removal of surface macromolecules by proteolytic digestion resulted in polymeric layers outside the cell surface that were less electrophoretically soft, and the cells therefore exhibited more negative and hydrophilic surface properties. Potentiometric titration results indicated that the total site concentration on the treated cells was approximately 22% smaller than untreated cells, while the dissociation constants were almost identical. This finding indicates little or no change in the composition of functional groups for untreated and proteinase K treated cells. The absence of surface macromolecules on treated cells, which are associated with polymeric substances enveloping the cell surface, was supported by Fourier transform infrared and transmission electron microscopy measurements. This information is critical for better understanding the role of surface macromolecules on E. coli O157:H7 interactions with various materials as well as cell-cell interactions.