Influence of Extracellular Polymeric Substances (EPS) on Deposition Kinetics of Bacteria

Abstract

The significance of extracellular polymer substances (EPS) on cell deposition on silica surfaces was examined by direct comparison of the deposition kinetics of untreated "intact" bacteria versus those from the same strain but with EPS removal via cation exchange resin (CER) treatment using a quartz crystal microbalance with dissipation (QCM-D). Four bacterial strains, mutant Escherichia coli BL21 (gram-negative, nonmotile), Pseudomonas sp QG6 (gram-negative, motile), Rhodococcus sp QL2 (gram-positive, nonmotile), and Bacillus subtilis (gram-positive, motile), were employed to determine the influence of EPS on cell deposition. Experiments were conducted in both monovalent (NaCl) and divalent (CaCl2) solutions under a variety of environmentally relevant ionic strength ranging from 1 to 100 mM at pH 6.0. The effectiveness of EPS removal via CER method was ensured by biochemical composition analysis of EPS solutions and further confirmed by FTIR analysis. Comparable zeta potentials were observed for untreated and CER treated bacterial cells in both NaCl and CaCl2 solutions, indicating that removal of EPS from cell surfaces via CER treatment did not affect the electrokinetic properties of the cell surfaces for all four strains. However, observed deposition efficiencies (alpha) were greater for untreated cells relative to those with CER treated cells across the entire ionic strength range examined in both NaCI and CaCl2 solutions for all four bacterial strains. These results strongly demonstrated that the removal of EPS from cell surfaces for all four strains decreased the deposition of bacteria on silica surfaces. This study clearly showed that the enhancement of cell deposition on silica surfaces due to the presence of EPS on cell surfaces was relevant to all bacterial strains examined regardless of cell types and motility.

Genetic Features of Resident Biofilms Determine Attachment of Listeria monocytogenes

“…Nevertheless, the biofilm volume reached that of the WT during the later stages of development (there were no differences in biovolume after 24 h of growth). This delayed biofilm formation could be attributed to the poor adhesive ability of EPS-producing cells under flow conditions, as was shown previously (39). The poor adhesive ability of EPS-producing cells could be explained by the shear forces caused by the laminar flow regimen prevailing in flow cells.…”

Bacteria use type-IV pili to slingshot on surfaces

“…Upon initial attachment to the surface, bacteria exhibit increased gene expression (32) for the production of EPS (33), which has been suggested as a precondition for irreversible attachment (34)(35)(36). For Pseudomonas, different components of the EPS appear to play different roles, with psl being more important for cell adhesion to surfaces (37), and pel being more important for cell-cell contact (38).…”

The role of cell-surface interactions in bacterial initial adhesion and consequent biofilm formation on nanofiltration/reverse osmosis membranes

“…The presence of EPS on the cell surface plays an important role in initial cell adhesion. Long et al [61] used a cation exchange treatment to remove EPS from the cell wall of several strains of bacteria and their deposition on silica surfaces at several ionic strengths was studied. The zeta potential and the size of the bacteria was the same for treated (EPS removal) and untreated bacteria: the treatment did not impact on the electrokinetic properties of the cell surface (zeta potential and mobility).…”