Deoxyribonucleic Acid Base Sequence Studies on Glucan-Producing and Glucan-Negative Strains of Streptococcus mitior

The deoxyribonucleic acid base sequence similarities among 14 strains of Streptococcus mitior were assessed by hybridization. Some strains produce glucan. Deoxyribonucleic acid was purified by both a conventional method and by centrifugation in CsCl. Hybridizations were done in solution with S1 nuclease and on membrane filters. The results showed two groups of moderately homologous strains. The glucan-producing strains represented a group which included some glucan-negative strains. Hybridization by the S1 method was less than with the filter method, indicating some sequence divergence within the two groups. There was a slight difference in guanine-plus-cytosine contents of the two groups.