Precursor-product relationship of intracellular and extracellular lipoteichoic acids of Streptococcus faecium.

Exponential biosynthesis and excretion of lipoteichoic acid (LTA) during the exponential phase of growth, and continued synthesis and excretion during valine starvation of Streptococcus faecium (S. faecalis ATCC 9790), were shown. During exponential growth, extracellular LTA (LTAx) accounted for approximately 13% of the total LTA in cultures, whereas during valine starvation, this percentage increased to approximately 60% within 4 h. LTAx was present in a low-molecular-weight, apparently deacylated form, whereas intracellular (LTAi) was present primarily in an apparently high-molecular-weight, acylated and micellar form. Experiments utilizing chases of either fully equilibrated or short pulses of [14C]- or [3H]glycerol were used to demonstrate that LTAx was derived directly from LTAi.