Characterization of Oral Streptococci That Activate the Dietary Glycoside Rutin to a Mutagen

Abstract

Oral streptococci are described that hydrolyze the dietary glycoside rutin (CAS: 153-18-4), resulting in mutagenic activity. Bacteria that hydrolyze rutin were isolated from the mouth of each of 10 healthy volunteers. The activity was inducible, and the product was mutagenic in the Salmonella mutagenicity assay. These bacteria were present in the greatest proportion on the dorsum of the tongue where they formed 1.5% of the total cultivable microflora. The appearance of the colonies, cell morphology, and biochemical characteristics were those of Streptococcus milleri. However, rutin hydrolysis did not occur with any of 30 isolates of this species from blood of patients with bacteremia, with any of 4 stock strains, or with any of 14 strains of streptococci from the other 4 major oral species. Therefore, activation of rutin to a mutagen is not a universal function of the normal oral flora, but it can be accomplished by some strains of S. milleri.