The addition of what can inhibit coaggregation?

• A. Specific sugars (like lactose)
• B. Metal ions
• C. Proteases
• D. High salt

Answer: (A)

Coaggregation between oral bacteria often depends on specific adhesin–carbohydrate interactions, where surface proteins recognize sugar moieties on partner cells. When you add free soluble sugars, they act as decoy receptors and bind to the adhesins, so the adhesins are occupied and cannot latch onto the carbohydrates on the other bacterial cell. That competitive binding blocks the cell–cell interaction required for coaggregation, making the process inhibit. Lactose is a concrete example of such a sugar that can interfere with these lectin-like adhesins.

Other factors aren’t as direct a match for this mechanism. Metal ions can alter surface properties or bridge interactions in some contexts but don’t specifically block the receptor–adhesin recognition that drives coaggregation. Proteases could degrade adhesins and reduce aggregation, but that depends on protease activity and isn’t a general, predictable inhibitor of coaggregation. High salt can disrupt weak electrostatic interactions, but many coaggregation events rely on specific carbohydrate recognition, which sugars specifically disrupt through competitive inhibition.