What type of adhesion occurs in coaggregation?

• A. Protein-protein
• B. Polysaccharide-lectin
• C. Lipid-lectin
• D. Nucleic acid-lectin

Answer: (B)

Coaggregation is driven by specific binding between different bacterial species on their cell surfaces, and this often involves a lectin–polysaccharide interaction. In this pattern, a lectin, which is a protein adhesin on one bacterium, recognizes and binds to a polysaccharide present on the surface of the partner bacterium. The carbohydrate on one cell acts as a receptor, and the protein on the other cell provides the binding site, creating a stable association that enables multispecies adhesion in a biofilm. This is why polysaccharide-lectin is the best description: it highlights the carbohydrate-based surface feature of one partner and the protein adhesin that binds it. The other patterns—protein–protein, lipid–lectin, or nucleic acid–lectin—do not capture the typical carbohydrate-mediated recognition seen in coaggregation of oral bacteria.