Interference Effects of Proteolytic Nattokinase on Biofilm Formation of Cariogenic Streptococci

Abstract

　Streptococcus mutans and S. sobrinus have been well recognized as principal etiological agents in human dental caries. We found that proteolytic enzyme nattokinase, which is found in a traditional fermented food "Natto" and belongs to the alkaline serine protease family, inhibited the sucrose-dependent biofilm formation of cariogenic streptococci. The presence of nattokinase resulted in the reduction of water-insoluble glucan, which promotes adhesion to the tooth surface and the aggregation of bacterial cells within a biofilm. This finding suggests that the inhibition of biofilm by nattokinase is based on its interference with key enzymes in water-insoluble glucan production. We also evaluated the effects of other serine and cysteine proteases on biofilm formation.