Abstract
Lytic ability and bacteriocin activity against Streptococcus (S.) sanguis ATCC 10556, 10557 and 10558 and artificial plaque forming ability by 119 strains of S. mutans were examined. Previously we have shown that 104 strains were serotype c/e/f and 15 were d/g.
Serotype c/e/f strains showed a fairly good lytic ability against S. sanguis ATCC 10558, but not against ATCC 10556 and 10557. They showed a higher bacteriocin activity against S. sanguis ATCC 10556 and 10557 than against ATCC 10558. In serotype d/g strains, a slight lytic ability against S. sanguis ATCC 10558 but not two others was seen, and an extremely slight bacteriocin activity against all S. sanguis strains was noted. The artificial plaque forming ability by d/g type strains was clearly higher than c/e/f type strains. These facts seem to show that these factors from S. mutans compensate for the defects of each other. From these results, it is probable that not only bacteriocin activity, but the lytic ability and artificial plaque forming ability of S. mutans also take part in the decrease of S. sanguis in the dental plaque.
