Effect of Cholate on the Incorporation of [¹⁴C]-Proline into the Cells of Staphylococcus aureus

Abstract

Staphylococcus aureus IFO 3060 is a salt-tolerant bacterium that can grow in medium containing from 0% to 15% NaCl. S. aureus grown in 5% NaCl medium accumulated large quantities of intracellular free proline. The addition of cholate to the medium resulted in an increase in the proportion of intracellular free proline to proline in protein fraction.
On the other hand, the incorporation of proline into cells of S. aureus was inhibited by adding cholate to 5% NaCl medium. The content of the intracellular free proline decreased to half as a result of inhibition. Furthermore, previous paper showed that the salt-tolerance of S. aureus was markedly weakened by adding cholate to the medium.
These results suggest that accumulated proline plays an important role in the mechanism of the osmoregulation of S. aureus. Lowering the function of the osmoregulation system by decreasing of free proline may weaken the salt-tolerance of S. aureus.