Which enzyme converts glucose to the sticky exopolysaccharide dextran in Streptococcus mutans?

• A. Amylase
• B. Protease
• C. Glucosyltransferase
• D. Lactase

Answer: (C)

Dextran is formed by an enzyme that links glucose units into a growing polysaccharide chain, creating the sticky matrix that helps Streptococcus mutans adhere to teeth. This process is carried out by glucosyltransferase, which transfers glucose residues and builds the dextran exopolysaccharide that composes the extracellular matrix of dental plaque. This matrix enables strong adhesion among cells and to the tooth surface, promoting biofilm formation and cariogenic potential. The other enzymes have unrelated roles: amylase breaks down starch, protease digests proteins, and lactase hydrolyzes lactose, none of which assemble glucose into dextran.