Pleiotropic compensation in the regulation of extracellular protein formation by a low alpha-toxin-producing variant of Staphylococcus aureus (Wood 46).

The changes in bacterial density, total extracellular protein and haemolysin produced by bacteria from overnight cultures of Staphylococcus aureus (Wood 46) and a low alpha-toxin-producing variant suspended in fresh medium were followed at 37 degrees C. Although five extracellular proteins were produced at a reduced level by the variant (alpha-toxin formation was reduced more than tenfold), the differential rates of total extracellular protein formation by the two organisms were identical. The results are consistent with a common regulatory mechanism for extracellular protein formation in which a pleiotropic compensation may occur in order to saturate the extracellular protein-producing capability.