title: Genetic heterogeneity in Streptococcus mutans.
abstract: The genetic homogeneity among eight cariogenic strains of Streptococcus mutans was assessed by deoxyribonucleic acid (DNA)-DNA reassociation experiments. DNA species were extracted from strains GS5, Ingbritt, 10449, FAl, BHT, E49, SLl, and KlR. Labeled DNA ((14)C-DNA) was extracted from strains 10449, FAl, and SLl. Denatured (14)C-DNA fragments were allowed to reassociate, i.e., form hybrid duplexes, with denatured DNA immobilized on membrane filters incubated in 0.45 m NaCl-0.045 m sodium citrate at 67 or 75 C. At 67 C, 10449 (14)C-DNA reassociated extensively only with GS5 and Ingbritt DNA. FAl (14)C-DNA hybridized extensively only with BHT DNA, and SLl (14)C-DNA reassociated with KlR and E49 DNA. DNA which hybridized extensively at 67 C also reassociated to a high degree at 75 C. Thermal elution of (14)C-FAl-BHT duplexes showed that the hybrid duplexes were thermostable. The results indicate that S. mutans is a genetically heterogeneous species. The strains studied can be divided into three (possibly four) genetic groups, and these groups closely parallel antigenic groups.
mesh_terms: D002247:Carbon Isotopes; D011232:Chemical Precipitation; D003470:Culture Media; D004269:DNA, Bacterial / Q000302:isolation & purification; D000431:Ethanol; D005374:Filtration; D005827:Genetics, Microbial; D006358:Hot Temperature; D006824:Hybridization, Genetic; D009691:Nucleic Acid Denaturation; D012703:Serotyping; D012964:Sodium; D012997:Solvents; D013291:Streptococcus / Q000145:classification* / Q000254:growth & development / Q000378:metabolism; D013431:Sulfates; D013501:Surface-Active Agents
chemical_list: D002247:Carbon Isotopes; D003470:Culture Media; D004269:DNA, Bacterial; D012997:Solvents; D013431:Sulfates; D013501:Surface-Active Agents; D000431:Ethanol; D012964:Sodium