Production of lipoteichoic acid by lactobacilli and streptococci grown in different environments

Representative strains of Streptococcus sanguis serotype 2 and of four Lactobacillus species were examined for the production of cellular and extracellular lipoteichoic acid (LTA) when grown at pH 6.0 in batch culture to the stationary phase with either glucose or fructose. Extracellular LTA was a minor component in all cases except for L. fermentum and L. casei NIRD R094 grown in fructose. The total amount of LTA (cellular and extracellular) produced by fructose-grown cultures was also considerably greater for these two strains, for L. salivarius, and also two of the S. sanguis strains. Growth of L. fermentum and L. casei in continuous culture in a chemostat showed that generation time and pH of growth can influence the total amount of LTA and the proportion of extracellular material. The results for glucose-limited cultures were quite disparate, with L. fermentum forming considerably more extracellular LTA than L. casei. However, in fructose-limited cultures L. fermentum formed less total LTA and L. casei more so that the differences were only minor. A difference in the utilization of glucose and fructose by the heterofermentative L. fermentum and the homofermentative L. casei strains is also indicated by differences in the yield of organisms at different dilution rates in continuous culture.