Inhibition of Streptococcus Mutans Glucosyltransferase by M-GTFI, a New Inhibitor

Abstract

Two hundred strains of soil microorganisms were screened for the production of inhibitors of the glucosyltransferase activity of Streptococcus mutans strain, Kl-R. The strain producing the greatest amount of inhibitor was one recently isolated in our laboratory. It has now been identified as a strain of Micromonospora narashinoensis on the basis of morphological and physiological studies.

The inhibitor, M-GTFI, affects the glucosyltransferase that produces the water-insoluble glucan rather than that which produces the watersoluble glucan. Fuchsin-sulphite staining of the inhibitor after its purification by polyacrylamide gel electrophoresis indicates that it is probably an acidic substance. It had Mr 5700 as was determined by gel filtration.

From an examination of the effects of this inhibitor on representative strains of S. mutans other than Kl-R, there is a suggestion of a similar selectivity for the waterinsoluble glucan-forming activity in other strains.

Key Words: :

• Glucosyltransferase inhibitor
• inhibitor
• M-GTFI
• Streptococcus mutans
• cariogenic glucan