Degradation of the microbial and salivary components participating in human dental plaque formation by proteases elaborated by plaque bacteria.

Twenty-eight strains of facultative, Gram-positive, sporulating bacilli which produce caseinolytic enzymes were isolated from human early dental plaque. A major component of the extracellular caseinolytic enzymes elaborated by strong producers seemed to be neutral zinc proteases. The extracellular proteases inactivated glucosyltransferase of Streptococcus mutans and inhibited the synthesis of adherent glucans from sucrose. The enzymes also degraded the Strep. mutans cell-surface receptor for dextran and glucan, the receptor for salivary agglutinins, located on Streptococcus sanguis cells, and the surface component of Actinomyces viscosus cells involved in co-agglutination with Strep. sanguis cells. The enzymes hydrolysed human whole saliva proteins, which seemed to result in loss of the ability to agglutinate Strep. sanguis cells.