| Abstract
| - The influence of the lipopolysaccharide (LPS) chain length on bacterial adhesion was investigated bymeasuring the collision efficiencies of three Escherichia coli K12 strains, each having a different lengthLPS, to silica glass beads in column tests (macroscale tests). Nanoscale interactions between the bacteriaand a silicon nitride tip were probed utilizing atomic force microscopy (AFM). Adhesion results based oncolumn tests indicated that collision efficiencies of the three bacteria were not consistently correlated toLPS length. Under conditions of low ionic strength (1 mM NaCl), collision efficiencies increased with LPSlength for the three strains of E. coli. However, if cells were fixed with glutaraldehyde (2.5%), the strainwith the shortest LPS chain had the greatest adhesion, while the bacterium with the mid-length LPS hadthe least adhesion to glass beads. Collision efficiencies increased when the solution ionic strength wasincreased from 1 to 100 mM as expected, and in most cases glutaraldehyde treatment also increasedadhesion. AFM force curves failed to distinguish the adhesion characteristics of these bacteria measuredin column tests, as all AFM force curves on the bacteria were identical. Changes in adhesion were alsonot predictable by more conventional measurements of bacterial properties based on ζ potential or contactangle. These results suggest that the LPS molecule length is not the sole determinant of adhesion of thethree E. coli strains in porous media and that AFM force curve analysis, zeta potential, or contact angledata cannot yet be used to fully predict adhesion of these three strains to glass beads.
|
