Abstract

Streptococcus mutans Ingbritt was grown in a chemostat at defined dilution rates and pH values and under carbohydrate limitation. At a constant dilution rate of D = 0.1 h-1 and with either 0.5% glucose or 0.5% sucrose, the amounts of both cellular and extracellular lipoteichoic acid increased as the culture pH increased from 5.0 to 7.5. At a constant pH of 6.0, the amount of cellular lipoteichoic acid formed by cultures growing in 0.2% or 0.5% glucose was relatively constant over a range of dilution rates, although the amount of extracellular lipoteichoic acid formed in 0.2% glucose at intermediate dilution rates was less than that formed in 0.5% glucose. Organisms grown in 0.5% sucrose at pH 6.0 contained increasing amounts of cellular lipoteichoic acid as the dilution rate was increased. A comparison of the amounts of cellular lipoteichoic acid formed by organisms growing at D = 0.5 h-1 and pH 6.0 in glucose, sucrose, fructose, or mixtures of glucose and fructose in limiting amounts suggested that the enhanced production of lipoteichoic acic by sucrose-grown organisms was due to the fructose component. The culture fluids from both glucose- and sucrose-grown organisms contained detectable amounts of serotype c antigen, whereas glucose-grown cultures also contained significant amounts of an extracellular hexose-containing polymer.