Use of an enzyme-linked lectinsorbent assay to monitor the shift in polysaccharide composition in bacterial biofilms

An enzyme-linked lectinsorbent assay (ELLA) was developed for quantificatio n and characterization of extracellular polysaccharides produced by 1- and 4-day biofilms of 10 bacterial strains isolated from food industry premises . Peroxidase-labeled concanavalin A (ConA) and wheat germ agglutinin (WGA) were used, as they specifically bind to saccharide residues most frequently encountered in biofilms matrices: D-glucose or D-mannose for ConA and N-ac etyl-D-glucosamine or N-acetylneuraminic acid for WGA. The ELLA applied to 1- and 4-day biofilms colonizing wells of microtiter plates was able to det ect that for Stenotrophomonas maltophilia and to a lesser extent Staphyloco ccus sciuri, the increase in production of exopolysaccharides over time was not the same for sugars binding with ConA and those binding with WGA. Diff erences in extracellular polysaccharides produced were observed among strai ns belonging to the same species. These results demonstrate that ELLA is a useful tool not only for rapid characterization of biofilm extracellular po lysaccharides but also, in studies of individual strains, for detection of changes over time in the proportion of the exopolysaccharidic component wit hin the polymeric matrix.