Survey of taurine uptake and metabolism in Staphylococcus aureus

Taurine has been reported to be a component of the capsular polysaccharide of the encapsulated M strain of Staphylococcus aureus. This led to a study of the uptake and metabolism of [1,2-14C]taurine in a variety of encapsulated and unencapsulated S. aureus strains. Taurine was taken up by all strains studied. A discrepancy between uptake measured as depletion of radioactivity from growth medium and as cell-associated radioactivity suggested that taurine may be catabolized to CO2 in some strains. In most strains, cell-associated radioactivity was located mainly in cold TCA-soluble (pool metabolites) fractions. About 90% of the cell-associated radioactivity was present in the pool metabolites fraction in the M strain, and about 10% in hot TCA-soluble (nucleic acid-teichoic acid-capsular polysaccharide) fraction. Radioactivity in spent medium and the capsular polysaccharide-containing fraction appeared to be present as taurine in this strain. Radioactivity in the pool metabolites fraction of three of the strains examined did not chromatograph as taurine, indicating that taurine was converted into other cell metabolites. One strain incorporated radioactivity from taurine into cellular macromolecules, thus revealing a heterogeneity of staphylococcal taurine metabolism.