Cariogenic actinomyces identified with a beta-glucosidase-dependent green color reaction to Gardenia jasminoides extract.

The oral bacteria Actinomyces naeslundii and Actinomyces viscosus are known to contribute to the initiation and progression of human dental caries, especially root caries. We report that both A. naeslundii and A. viscosus react with a component in the Gardenia jasminoides extract to produce a distinct green product. This green color reaction was found to be dependent on the bacterial beta-glucosidase. The reaction is specific for cariogenic actinomyces, and it can detect as few as 10(4) cells of A. naeslundii and A. viscosus per ml.