Interactions of selenium and fluoride on growth, glycolysis and survival of Streptococcus mutans GS-5

The effects of low concentrations (1.0 mmol/l of selenite and seleno-dl-cystine were tested alone, or in combination with NaF, on growth, glycolysis, and survival of Streptococcus mutans GS-5. In batch culture, both selenium-containing compounds (1.0 mmol/l) inhibited the growth rate and final cell yield by 92% or greater; glycolysis, however, was not affected. The observed bactericidal action of selenite at 0.1 mmol/l was pH-dependent. Fluoride reduced the killing effect of SeO3 in the culture medium and in a lactate-acetate buffer system at pH 6.5, 5.0 and 4.0. These data indicate that selenium-containing compounds exert an antibacterial action on cells of S. mutans in a manner which leaves glycolysis unaffected.