Effect of dextranase and protease enzymes on aggregation of Streptococcus mutans: colorimetric and electron microscopic studies

Graves, W. and Verran, Joanna (1984) Effect of dextranase and protease enzymes on aggregation of Streptococcus mutans: colorimetric and electron microscopic studies. Microbios, 40 (161-2). pp. 145-152. ISSN 0026-2633

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Abstract

Sucrose-induced aggregation of Streptococcus mutans was ascertained by measuring the decrease in optical density of a cell suspension after 20 h incubation. The optimum sucrose concentration for the aggregation assay was 5% w/v, at an incubation temperature of 37 degrees C. Dextranase and protease enzymes were added to the suspensions to determine their effects on aggregation. Dextranase treatment decreased aggregation. Electron microscopic studies revealed a reduction in the amount of a diffuse coat which surrounded cells in the absence of the enzyme but in the presence of sucrose, and a degradative effect on fibrous extracellular material. Protease treatment of suspensions produced an increase in optical density; cell aggregates were not apparent. Electron microscopic studies revealed extensive cell damage and lysis. The success of these enzymes in decreasing aggregation would indicate a role in both caries and plaque control in vivo.