Affiliation:
1. Unité de Chimie des Interfaces, Université Catholique de Louvain, Place Croix du Sud 2/18, B-1348 Louvain-la-Neuve, Belgium
2. F. A. Janssens Laboratory of Genetics, Catholic University of Leuven, Willem de Croylaan 42, B-3001 Heverlee, Belgium
Abstract
Adhesion of Azospirillum brasilense to glass and polystyrene was investigated by bringing the cells into contact with the support by sedimentation. Adhesion depended on time and temperature: lower adhesion densities were observed when the contact time was only 2 h or 6 h, as compared to 24 h, or when the test was performed at 4 -C, as compared to 30 °. The influence of cell physiology was further demonstrated by the effect of tetracycline, which inhibited adhesion. Scanning electron microscopy showed that cells produced extracellular material when left in contact with a support for 24 h. The surface elemental composition of cells and of polystyrene supports after cell adhesion and subsequent detachment was determined by X-ray photoelectron spectroscopy; this provided information on the relative concentrations of proteins and polysaccharides at the surface. The protein concentration at the surface of a cell sediment increased as a function of time at 30 °, correlating with an increase of adhesion density. A similar correlation between protein concentration and adhesion density was found when comparing exponentialphase cells with stationary-phase cells. The surface composition of polystyrene supports examined after cell detachment was found to be rich in proteins, indicating that proteins are the major constituent at the support surface. Lowering the contact time, or performing adhesion under unfavourable metabolic conditions (4 °) or in the presence of tetracycline, resulted in a decrease in protein concentration at the support surface, which was correlated with a decrease in adhesion density. The correlation between protein concentration at the cell surface or at the support surface and adhesion density, under different experimental conditions, provides a direct demonstration of the involvement of extracellular proteins in the adhesion of A. brasilense to inert surfaces.
Reference52 articles.
1. Surface thermodynamics of bacterial adhesion;Absolom;Appl Environ Microbiol,1983
2. The role of exopolysaccharides in adhesion of freshwater bacteria;Allison;J Gen Microbiol,1987
3. Anchoring of Azospirillum brasilense to hydrophobic polystyrene and wheat roots;Bashan;J Gen Microbiol,1993
4. Active attachment of A%o-spirillum brasilense Cd to quartz sand and to a light-textured soil by protein bridging;Bashan;J Gen Microbiol,1988
5. Evidence for a weak active external adsorption of Azospirillum brasilense Cd to wheat roots;Bashan;J Gen Microbiol,1986
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