Microbial Community Analysis of a Methane-Producing Biocathode in a bioelectrochemical System
Eerten-Jansen, M.C.A.A. van; Veldhoen, A.B. ; Plugge, C.M. ; Stams, A.J.M. ; Buisman, C.J.N. ; Heijne, A. ter - \ 2013
Archaea : an international microbiological journal 2013 (2013). - ISSN 1472-3646 - 12 p.
caeni sp nov. - fuel-cells - bacterial adhesion - activated-sludge - electrolysis cells - carbon-dioxide - gen. nov. - performance - reduction - acetate
A methane-producing biocathode that converts CO2 into methane was studied electrochemically and microbiologically. The biocathode produced methane at a maximum rate of 5.1¿L¿CH4/m2 projected cathode per day (1.6¿A/m2) at -0.7¿V versus NHE cathode potential and 3.0¿L¿CH4/m2 projected cathode per day (0.9¿A/m2) at -0.6¿V versus NHE cathode potential. The microbial community at the biocathode was dominated by three phylotypes of Archaea and six phylotypes of bacteria. The Archaeal phylotypes were most closely related to Methanobacterium palustre and Methanobacterium aarhusense. Besides methanogenic Archaea, bacteria seemed to be associated with methane production, producing hydrogen as an intermediate. Biomass density varied greatly with part of the carbon electrode covered with a dense biofilm, while only clusters of cells were found on other parts. Based on our results, we discuss how inoculum enrichment and changing operational conditions may help to increase biomass density and to select for microorganisms that produce methane.
Pluronic-lysozyme conjugates as anti-adhesive and antibacterial bifunctional polymers for surface coating
Muszanska, A.K. ; Busscher, H.J. ; Herrmann, A. ; Mei, H.C. van der; Norde, W. - \ 2011
Biomaterials 32 (2011)26. - ISSN 0142-9612 - p. 6333 - 6341.
egg-white lysozyme - protein adsorption - bacterial adhesion - block-copolymers - hydrophobic surfaces - grafting density - biomaterials - brushes - temperature - interfaces
This paper describes the preparation and characterization of polymer protein conjugates composed of a synthetic triblock copolymer with a central polypropylene oxide (PPO) block and two terminal polyethylene oxide (PEO) segments, Pluronic F-127, and the antibacterial enzyme lysozyme attached to the telechelic groups of the PEO chains. Covalent conjugation of lysozyme proceeded via reductive amination of aldehyde functionalized PEO blocks (CHO-Pluronic) and the amine groups of the lysine residues in the protein. SDS-PAGE gel electrophoresis together with MALDI-TOF mass spectrometry analysis revealed formation of conjugates of one or two lysozyme molecules per Pluronic polymer chain. The conjugated lysozyme showed antibacterial activity towards Bacillus subtilis. Analysis with a quartz crystal microbalance with dissipation revealed that Pluronic lysozyme conjugates adsorb in a brush conformation on a hydrophobic gold-coated quartz surface. X-ray photoelectron spectroscopy indicated surface coverage of 32% by lysozyme when adsorbed from a mixture of unconjugated Pluronic and Pluronic lysozyme conjugate (ratio 99:1) and of 47% after adsorption of 100% Pluronic-lysozyme conjugates. Thus, bifunctional brushes were created, possessing both anti-adhesive activity due to the polymer brush, combined with the antibacterial activity of lysozyme. The coating having a lower degree of lysozyme coverage proved to be more bactericidal.
Interfacial re-arrangement in initial microbial adhesion to surfaces
Busscher, H.J. ; Norde, W. ; Sharma, P.K. ; Mei, H.C. van der - \ 2010
Current Opinion in Colloid and Interface Science 15 (2010)6. - ISSN 1359-0294 - p. 510 - 517.
quartz-crystal microbalance - atomic-force microscopy - fibronectin-binding proteins - plate flow chamber - escherichia-coli - ionic-strength - staphylococcus-epidermidis - bacterial adhesion - streptococcus-mutans - parallel-plate
Upon initial microbial adhesion to a surface multiple events occur that include interfacial re-arrangements in the region between an adhering organism and a surface Application of physico-chemical mechanisms to explain microbial adhesion to surfaces requires better knowledge of the interfacial re arrangement occurring immediately after adhesion than hitherto available
Poisson analysis of streptococcal bond strengthening on stainless steel with and without salivary conditioning film
Mei, Li ; Mei, H.C. van der; Ren, Y. ; Norde, W. ; Busscher, H.J. - \ 2009
Langmuir 25 (2009)11. - ISSN 0743-7463 - p. 6227 - 6231.
atomic-force microscopy - bacterial adhesion - surface - hydrophobicity - charge
Poisson analysis of retract force-distance curves in atomic force microscopy (AFM) has yielded a new dimension to the decoupling of individual bond forces into a hydrogen bonding and nonspecific force component. Accordingly, bacterial adhesion forces have been decoupled into a hydrogen bonding and nonspecific Lifshitz-Van der Waals contribution. Due to the forced nature of AFM contact, the nonspecific force contribution has hitherto turned out to be repulsive in the analysis of bacterial adhesion forces on nonconducting surfaces. In this study, we present the results of a Poisson analysis of adhesion forces for streptococci adhering to a conducting surface. Adhesion forces measured between stainless steel, both in the absence and presence of an adsorbed salivary conditioning film, increased with increasing contact time between the streptococcal AFM probe and the surface. Concurrent with the increase in adhesion force, there was an increase in the number of minor force peaks in the retract force-distance curves. Poisson analyses of the adhesion forces indicated repulsive nonspecific Lifshitz-Van der Waals forces for streptococci adhering to saliva-coated stainless steel, but interestingly and for the first time, attractive nonspecific forces were revealed on stainless steel in the absence of a salivary conditioning film. We tentatively attribute this to attraction between the negatively charged streptococci and their positive image charges in the conducting material, which cannot develop in a nonconducting material or in the presence of a nonconductive protein layer on the stainless steel surface.
Mobile and immobile adhesion of staphylococcal strains to hydrophilic and hydrophobic surfaces
Boks, N.P. ; Kaper, H.J. ; Norde, W. ; Mei, H.C. van der; Busscher, H.J. - \ 2009
Journal of Colloid and Interface Science 331 (2009)1. - ISSN 0021-9797 - p. 60 - 64.
bacterial adhesion - biofilm reactors - infections - attachment - deposition - reversibility - substrata - energies - system - flow
Staphylococcus epidermidis adheres to hydrophilic glass and hydrophobic dimethyldichlorosilane (DDS)-coated glass in similar numbers, but in different modes. Real-time observation of staphylococcal adhesion under a shear rate of 15 s(-1) revealed different adhesion dynamics on both substrata. The number of adsorption and desorption events to achieve a similar number of adhering bacteria was twofold higher on hydrophilic than on hydrophobic DDS-coated glass. Moreover. 22% of all staphylococci on glass slid over the surface prior to adhering on a fixed site ("mobile adhesion mode"), but mobile adhesion was virtually absent (1%) on DDS-coated glass. Sliding preceded desorption on hydrophilic glass in about 20% of all desorption events, while on hydrophobic DDS-coated glass 2% of all staphylococci desorbed straight from their adhesion site. Since acid-base interactions between the staphylococci and a hydrophobic DDS-coating are attractive, it is suggested that these interactions facilitate a closer approach of the bacteria and therewith enhance immobile adhesion at local, high affinity sites. Alternatively, if the local site is low affinity, this may lead to desorption. In the absence of attractive acid-base interactions, as on hydrophilic glass, bacteria can be captured in the minimum of the DLVO-interaction energy curve, but this does not prevent them from sliding under flow at a fixed distance from a substratum surface until immobilization or desorption at or from a local high or low affinity site, respectively.
Fermented soya bean (tempe) extracts reduce adhesion of enterotoxigenic Escherichia coli to intestinal epithelial cells
Roubos-van den Hil, P.J. ; Nout, M.J.R. ; Beumer, R.R. ; Meulen, J. van der; Zwietering, M.H. - \ 2009
Journal of Applied Microbiology 106 (2009)3. - ISSN 1364-5072 - p. 1013 - 1021.
rhizopus-oligosporus - disease prevention - bacterial adhesion - food - diarrhea - k88 - enterocytes - inhibition - piglets - caco-2
Aims: This study aimed to investigate the effect of processed soya bean, during the successive stages of tempe fermentation and different fermentation times, on adhesion of enterotoxigenic Escherichia coli (ETEC) K88 to intestinal brush border cells as well as Caco-2 intestinal epithelial cells; and to clarify the mechanism of action. Methods and Results: Tempe was prepared at controlled laboratory scale using Rhizopus microsporus var. microsporus as the inoculum. Extracts of raw, soaked and cooked soya beans reduced ETEC adhesion to brush border cells by 40%. Tempe extracts reduced adhesion by 80% or more. ETEC adhesion to Caco-2 cells reduced by 50% in the presence of tempe extracts. ETEC K88 bacteria were found to interact with soya bean extracts, and this may contribute to the observed decrease of ETEC adhesion to intestinal epithelial cells. Conclusions: Fermented soya beans (tempe) reduce the adhesion of ETEC to intestinal epithelial cells of pig and human origin. This reduced adhesion is caused by an interaction between ETEC K88 bacteria and soya bean compounds. Significance and Impact of the Study: The results strengthen previous observations on the anti-diarrhoeal effect of tempe. This effect indicates that soya-derived compounds may reduce adhesion of ETEC to intestinal cells in pigs as well as in humans and prevent against diarrhoeal diseases.
Residence time dependent desorption of Staphylococcus epidermidis from hydrophobic and hydrophilic substrata
Boks, N.P. ; Kaper, H.J. ; Norde, W. ; Busscher, H.J. ; Mei, H.C. van der - \ 2008
Colloids and Surfaces. B: Biointerfaces 67 (2008)2. - ISSN 0927-7765 - p. 276 - 278.
plate flow chamber - bacterial adhesion - colloidal particles - surfaces - deposition - forces - model - stiffness - kinetics
Adhesion and desorption are simultaneous events during bacterial adhesion to surfaces. although desorption is far less studied than adhesion. Here, desorption of Staphylococcus epidermidis from substratum surfaces is demonstrated to be residence time dependent. Initial desorption rate coefficients were similar for hydrophilic and hydrophobic dimethylclichlorosilane (DDS)-coated glass, likely because initial desorption is controlled by attractive Lifshitz-Van der Waals interactions, which are comparable on both substratum Surfaces. However, significantly slower decay times of the desorption rate coefficients are found for hydrophilic glass than for hydrophobic DDS-coated glass. This difference is suggested to be due to the acid-base interactions between staphylococci and these surfaces, which are repulsive on hydrophilic glass and attractive on hydrophobic DDS-coated glass. Final desorption rate coefficients are higher on hydrophilic glass than on hydrophobic DDS-coated glass, due to the so called hydrophobic effect, facilitating a closer contact on hydrophobic DDS-coated glass.
Surface-tethered polymers to influence protein adsorption and microbial adhesion
Norde, W. - \ 2007
Zeitschrift für Physikalische Chemie 221 (2007)1. - ISSN 0942-9352 - p. 47 - 63.
poly(ethylene oxide) brushes - solid-liquid interfaces - bacterial adhesion - model proteins - chain-length - temperature - parameters - stability - coatings
In various applications it is desired that biological cells or protein molecules are immobilized at surfaces. Examples are enzymes or cells in bioreactors and biosensors, immuno-proteins in solid-state diagnostics and proteinaceous farmacons in drug delivery systems. In order to retain biological activity, the structural integrity of the immobilized bio-compounds should be preserved. In other cases immobilization of cells and proteins should be avoided. Adsorption of proteins from biofluids is considered to be the first event in the biofouling process. Subsequently, bacterial and/or other biological cells (e.g., blood platelets, erythrocytes) deposit on the adsorbed protein layer and a biofilm is formed. This causes great problems in areas as diverse as biomedicine, food processing and the marine environment. A generic approach to influence the magnitude of the interaction between a particle (e.g., a cell or a globular protein molecule) and a sorbent material is to manipulate both the long- and short-range interaction forces by grafting soluble polymers or oligomers onto the sorbent surface. Application of oligomers of ethylene oxide (EO) prevents the particles from making intimate contact with the surface. Thus, adsorbed enzymes may retain their native structure and, hence, their enzymatic activity. Another interesting example is the steering effect of pre-adsorbed polymers of EO (PEO) on the orientation of subsequently depositing anisotropic particles. For instance, IgG molecules may be forced in the right orientation and conformation in the interstitial spaces between the PEO chains, therewith doubling the specific antigen binding capacity. By far the greatest part of recent research on modifying surfaces by grafting soluble polymers (usually PEO) aims at the prevention of protein adsorption and/or adhesion of biological cells. Suppression of particle deposition depends primarily on two characteristics of the polymer layer: (a) the grafting density, and (b) the extension of the polymer layer into the solution. The efficacy of grafted PEO layers to reduce protein adsorption and microbial adhesion is illustrated for blood plasma proteins, saliva proteins and a number of bacterial and yeast cells.
Probing surface structures of Shewanella spp. by microelectrophoresis
Dague, E. ; Duval, J.F.L. ; Jorand, R. ; Thomas, F. ; Gaboriaud, F. - \ 2006
Biophysical Journal 90 (2006)7. - ISSN 0006-3495 - p. 2612 - 2621.
streptococcus-mitis strains - diffuse soft interfaces - electrophoretic mobility - bacterial adhesion - particle analysis - cell - putrefaciens - reduction - fe(iii) - alga
Long-range electrostatic forces substantially influence bacterial interactions and bacterial adhesion during the preliminary steps of biofilm formation. The strength of these forces depends strongly on the structure of the bacterium surfaces investigated. The latter may be addressed from appropriate analysis of electrophoretic mobility measurements. Due to the permeable character of the bacterium wall and/or surrounding polymer layer, bacteria may be regarded as paradigms of soft bioparticles. The electrophoretic motion of such particles in a direct-current electric field differs considerably from that of their rigid counterparts in the sense that electroosmotic flow takes place around and within the soft surface layer. Recent developments of electrokinetic theories for soft particles now render possible the evaluation of the softness degree ( or equivalently the hydrodynamic permeability) from the raw electrokinetic data. In this article, the electrophoretic mobilities of three Shewanella strains (MR-4, CN32, and BrY) presenting various and well-characterized phenotypes of polymer fringe are reported over a wide range of pH and ionic strength conditions. The data are quantitatively analyzed on the basis of a rigorous numerical evaluation of the governing electrostatic and hydrodynamic equations for soft particles. It is clearly shown how the peculiar surface structures of the bacteria investigated are reflected in their electrohydrodynamic properties.
The use of positively charged or low surface free energy coatings versus polymer brushes in controlling biofilm formation
Roosjen, A. ; Norde, W. ; Mei, H.C. van der; Busscher, H.J. - \ 2006
Progress in Colloid and Polymer Science 132 (2006). - ISSN 0340-255X - p. 138 - 144.
coagulase-negative staphylococci - poly(ethylene oxide) brushes - self-assembled monolayers - bacterial adhesion - polyethylene-glycol - protein adsorption - polystyrene surfaces - biomedical polymers - microbial adhesion - parallel-plate
Biofilm formation on biomaterials implant surfaces and subsequent infectious complications are a frequent reason for failure of many biomedical devices, such as total hip arthroplasties, vascular catheters and urinary catheters. The development of a biofilm is initiated by the formation of a conditioning film of adsorbed macromolecules, such as proteins, followed by adhesion of microorganisms, where after they grow and anchor through secretion of extracellular polymeric substances. Adhesion of microorganisms is influenced by the physico-chemical properties of the biomaterial surface. Positively charged materials stimulate bacterial adhesion, but prevent growth of adhering bacteria. The use of low surface free energy materials did not always reduce in vitro adhesion of bacteria, but has been found beneficial in in vivo applications where fluctuating shear forces prevail, like on intra-oral devices and urine catheters. Polymer brushes have shown a very high reduction in in vitro adhesion of a great variety of microorganisms. However, for clinical application, the long term stability of polymer brushes is still a limiting factor. Further effort is therefore required to enhance the stability of polymer brushes on biomaterial implant surfaces to facilitate clinical use of these promising coatings
Influence of shear on microbial adhesion to PEO-brushes and glass by convective-diffusion and sedimentation in a parallel plate flow chamber
Roosjen, A. ; Boks, N.P. ; Mei, H.C. van der; Busscher, H.J. ; Norde, W. - \ 2005
Colloids and Surfaces. B: Biointerfaces 46 (2005)1. - ISSN 0927-7765 - p. 1 - 6.
bacterial adhesion - chain-length - surfaces - deposition - resistance - attachment - stress
Microbial adhesion to surfaces often occurs despite high wall shear rates acting on the adhering microorganisms. In this paper, we compare the wall shear rates needed to prevent microbial adhesion to bare glass and poly(ethylene oxide) (PEO)-brush coated glass in a parallel plate flow chamber. Initial microbial deposition rates were determined for different wall shear rates between 4 and 1600 s¿1 on the top and bottom plates of the flow chamber. Deposition efficiencies ¿SL, based on the Smoluchowski¿Levich approach, for Pseudomonas aeruginosa D1, Escherichia coli O2K2 and Candida tropicalis GB 9/9 decreased with increasing wall shear rates and were lower for PEO-brush coated glass than for bare glass. Characteristic shear rates preventing adhesion to the bottom plate were around 10 and 1.0 s¿1 for the bacteria on glass and the PEO-brush and 36 and 3.4 s¿1 for the yeast strain on glass and the PEO-brush, respectively. This demonstrates that the adhesive forces between microorganisms and a PEO-brush are comparatively weak, although some strains may have the ability to adhere to a PEO-brush under low shear conditions. Microbial deposition efficiencies ¿SL were much larger, however, than unity for bottom plate deposition, but could be reduced to realistic values by averaging the deposition rates found for the top (negative contribution of sedimentation) and bottom (positive contribution of sedimentation) plates.
Role of lactobacillus cell surface hydrophobicity as probed by AMF in adhesion to surfaces at low and high ionic strength
Vadillo-Rodriguez, V. ; Busscher, H.J. ; Meij, H.C. van der; Vries, J. de; Norde, W. - \ 2005
Colloids and Surfaces. B: Biointerfaces 41 (2005)1. - ISSN 0927-7765 - p. 33 - 41.
scanning force microscopy - plate flow cell - colloidal particles - bacterial adhesion - functional-groups - escherichia-coli - layer proteins - image-analysis - deposition - adsorption
The S-layer present at the outermost cell surface of some lactobacillus species is known to convey hydrophobicity to the lactobacillus cell surface. Yet, it is commonly found that adhesion of lactobacilli to solid substrata does not proceed according to expectations based on cell surface hydrophobicity. In this paper, the role of cell surface hydrophobicity of two lactobacillus strains with and without a surface layer protein (SLP) layer has been investigated with regard to their adhesion to hydrophobically or hydrophilically functionalized glass surfaces under well-defined flow conditions and in low and high ionic strength suspensions. Similarly, the interaction of the lactobacilli with similarly functionalized atomic force microscope (AFM) tips was measured. In a low ionic strength suspension, both lactobacillus strains show higher initial deposition rates to hydrophobic glass than to hydrophilic glass, whereas in a high ionic strength suspension no clear influence of cell surface hydrophobicity on adhesion is observed. Independent of ionic strength, however, AFM detects stronger interaction forces when both bacteria and tip are hydrophobic or hydrophilic than when bacteria and tip have opposite hydrophobicities. This suggest that the interaction develops in a different way when a bacterium is forced into contact with the tip surface, like in AFM, as compared with contacts developing between a cell surface and a macroscopic substratum under flow. In addition, the distance dependence of the total Gibbs energy of interaction could only be qualitatively correlated with bacterial deposition and desorption in the parallel plate flow chamber.
Relations between macroscopic and microscopic adhesion of Streptococcus mitis strains to surfaces
Vadillo-Rodriguez, V. ; Busscher, H.J. ; Norde, W. ; Vries, J. de; Mei, H.C. van der - \ 2004
Microbiology 150 (2004). - ISSN 1350-0872 - p. 1015 - 1022.
atomic-force microscopy - bacterial adhesion - escherichia-coli - flow chamber - cell - attachment - polymers - hydrophobicity - deposition - sanguis
Application of physico-chemical models to describe bacterial adhesion to surfaces has hitherto only been partly successful due to the structural and chemical heterogeneities of bacterial surfaces, which remain largely unaccounted for in macroscopic physico-chemical characterizations of the cell surfaces. In this study, the authors attempted to correlate microscopic adhesion of a collection of nine Streptococcus mitis strains to the negatively charged, hydrophilic silicon nitride tip of an atomic force microscope (AFM) with macroscopic adhesion of the strains to a negatively charged, hydrophilic glass in a parallel-plate flow chamber. The repulsive force probed by AFM upon approach of the tip to a bacterial cell surface ranged from 1·7 to 7·7 nN depending on the strain considered and was found to correspond to an activation barrier, governing initial, macroscopic adhesion of the organisms to the glass surface. Moreover, maximum distances at which attractive forces were probed by the AFM upon retraction of the tip (120 to 1186 nm) were related to the area blocked by an adhering bacterium, i.e. the distance kept between adhering bacteria. Bacterial desorption could not be related to adhesive forces as probed by the AFM, possibly due to the distinct nature of the desorption process occurring in the parallel-plate flow chamber and the forced detachment in AFM.
Microbial adhesion to poly(ethylene oxide) brushes: Influence of polymer chain length and temperature
Roosjen, A. ; Mei, H.C. van der; Busscher, H.J. ; Norde, W. - \ 2004
Langmuir 20 (2004)25. - ISSN 0743-7463 - p. 10949 - 10955.
self-assembled monolayers - protein adsorption - polyethylene oxide - bacterial adhesion - stainless-steel - glycol) chains - surfaces - dependence - resistance - density
Glass surfaces were modified by end-grafting poly(ethylene oxide) (PEO) chains having molecular weights of 526, 2000, or 9800 Da. Characterization using water contact angles, ellipsometry, and X-ray photoelectron spectroscopy confirmed the presence of the PEO brushes on the surface with estimated lengths in water of 2.8-, 7.5-, and 23.7-nm, respectively. Adhesion of two bacterial (Staphylococcus epidermidis and Pseudomonas aeruginosa) and two yeast (Candida albicans and Candida tropicalis) strains to these brushes was studied and compared to their adhesion to bare glass. For the bacterium P. aeruginosa and the yeast C. tropicalis, adhesion to the 2.8-nm brush was comparable to their adhesion on bare glass, whereas adhesion to the 7.5- and 23.7-nm brushes was greatly reduced. For S. epidermidis, adhesion was only slightly higher to the 2.8-nm brush than that to the longer brushes. Adhesion of the yeast C. albicans to the PEO brushes was lower than that to glass, but no differences in adhesion were found between the three brush lengths. After passage of an air bubble, nearly all microorganisms adhering to a brush were removed, irrespective of brush length, whereas retention of the adhering organisms on glass was much higher. No significant differences were found in adhesion nor retention between experiments conducted at 20 and those conducted at 37 C.
Atomic force microscopic corroboration of bond ageing for adhesion of Streptococcus thermophilus to solid substrata
Vadillo-Rodriguez, V. ; Busscher, H.J. ; Norde, W. ; Vries, J. de - \ 2004
Journal of Colloid and Interface Science 278 (2004)1. - ISSN 0021-9797 - p. 251 - 254.
plate flow chamber - bacterial adhesion - particle deposition - colloidal particles - polymers - surfaces - adsorption
Initial bacterial adhesion is considered to be reversible, but over time the adhesive bond between a bacterium and a substratum surface may strengthen, turning the process into an irreversible state. Microbial desorption has been studied in situ in controlled flow devices as a function of the organisms resident time on the surface (J. Colloid Interface Sci. 164 (1994) 355). It appeared that desorption of Streptococcus thermophilus decreased strongly within approximately 50 s after initial adhesion due to bond aging. In this paper, bond aging between the S. thermophilus cell surface and the silicon nitride tip of an AFM (atomic force microscope) is corroborated microscopically and related to the macroscopic, residence time-dependent desorption of the organism under flow. AFM indicated bond strengthening between the tip and the cell surface within 100 s of contact, which is on the same order of magnitude as bond aging inferred from residence time-dependent desorption. Comparison of the interaction energies derived from AFM and macroscopic desorption indicate that bond strengthening arises as a result of multiple attachments of extracellular polymeric substances to a substratum surface.
Characterization of (polyethylene oxide) brushes on glass surfaces and adhesion of Staphylococcus epidermidis
Kaper, H.J. ; Busscher, H.J. ; Norde, W. - \ 2003
Journal of Biomaterials Science-Polymer Edition 14 (2003)4. - ISSN 0920-5063 - p. 313 - 324.
self-assembled monolayers - protein adsorption - bacterial adhesion - polyethylene oxide - polymer brushes - model - particles
Poly(ethylene oxide) brushes have been covalently bound to glass surfaces and their presence was demonstrated by an increase in water contact angles from fully wettable on glass to advancing contact angles of 54 degrees, with a hysteresis of 32 degrees. In addition, electrophoretic mobilities of glass and brush-coated glass were determined using streaming potential measurements. The dependence of the electrophoretic mobilities on the ionic strength was analyzed in terms of a softlayer model, yielding an electrophoretic softness and fixed charge density of the layer. Brush-coated glass could be distinguished from glass by a 2-3-fold decrease in fixed charge density, while both surfaces were about equally soft. Adhesion of Staphylococcus epidermidis HBH276 to glass in a parallel plate flow chamber was extremely high and after 4 h, 19.0 x 10(6) bacteria were adhering per cm2. In contrast, the organisms did not adhere to brush-coated glass, with numbers below the detection limit, i.e. 0.1 x 10(6) per cm2. These results attest to the great potential of polymer brushes in preventing bacterial adhesion to surfaces.