Abstract
Human salivary lysozyme (HSL) was purified from human saliva and added to cultures of Streptococcus mutans. 14C-2-deoxyglucose incorporation, L-(+)-lactic acid production from glucose and the number of viable cells were then determined. Both sugar incorporation and lactic acid production were inversely related to the lysozyme concentration and the time of lysozyme treatment. At a lysozyme activity corresponding to 20.0 μg/ml hen egg white lysozyme, the amount of sugar taken up after 30 min was reduced by approximately 50%. No L-(+)-lactic acid was detected after 3 h of incubation. Strains of S. mutans of serotypes b and c were susceptible to the action of HSL, whereas serotypes a, d and e were resistant. A significant reduction in viable cell count was found for strains BHT (b) and Ingbritt (c) after 2 h of incubation with HSL. The results suggest that the reduction in sugar uptake and acid production was due to initial damage of the bacterial cell membrane and a reduced number of viable cells.