STREPTOCOCCUS-MUTANS ISOLATES IDENTIFIED BY BIOCHEMICAL TESTS AND DNA-BASE CONTENTS

Fifty-five strains of Streptococcus mutans were isolated from dental plaque in a clinical survey of the presence of this species and others resembling it. The species identifications were based on biochemical tests; determination of DNA base contents (mol per cent G + C) of 43 isolates confirmed the identifications. The results showed that Strep. mutans, as currently defined, can be easily and reliably identified by biochemical tests, and that DNA of clinical isolates have the expected 36 to 38 mol per cent guanine plus cytosine. Strep. mutans was clearly the predominant Strep. mutans-like streptococcus in the population sampled. © 1978.