Preferential utilization of the glucosyl moiety of sucrose by a cariogenic strain of Streptococcus mutans.

The utilization of sucrose by a cariogenic strain of Streptococcus mutans was studied. The soluble and cell-bound sucrose-dependent, polymer-forming sucrase activities constitutively produced by the bacteria during growth on glucose were measured. About eight times more dextransucrase activity was present than levan-sucrase activity. During various states of growth on sucrose, S. mutans accumulated two to five times more insoluble and water-soluble dextran than levan. Although more of the fructosyl moiety of sucrose was therefore available to the cells, the glucosyl portion of the disaccharide was preferentially incorporated into cellular macromolecules. Glucose was shown to inhibit the utilization of fructose by S. mutans.