Enhanced production of cell-bound and extracellular streptolysin S by hemolytic streptococci pretreated with proteases.

The amount of streptolysin S produced by resting streptococci was considerably increased after incubation of the washed bacteria with trypsin or pronase. Production of both cell-bound and free forms of the toxin was enhanced by the protease treatment. By addition of trypsin, streptolysin S yield was considerably increased in growing culture as well. Treatment with lysozyme was ineffective, and the toxin production was only slightly promoted by preincubation with hyaluronidase or chymotrypsin. In contrast, pretreatment with chymotrypsin caused increased production of an extracellular nuclease, whereas the yield of this enzyme was reduced after incubation of the cocci with pronase. Evidence was obtained indicating de novo synthesis of the exotoxin in the protease-treated bacteria.