| 摘要 |
Mutant strains have been isolated from Streptococcus mutans strain BHT-2(str) which are characterized by a single point mutation in the structural gene for the enzyme, L(+) lactate dehydrogenase, this enzyme being normally responsible for lactic acid production by this bacterium. Streptococcus mutans is believed to be a principal pathogen in dental caries, a disease characterized by the dissolution of the mineral portion of the tooth caused by acid resulting from the interaction of bacteria on the tooth surface with carbohydrates. The mutant strains of the invention will be found useful as prototype nonvirulent effector strains in controlling the incidence and severity of dental caries.
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