EXPRESSION OF STREPTOLYSIN-O GENE IN BACILLUS-SUBTILIS

Streptolysin O (SLO) is a hemolytic, extracellular protein produced by Streptococcus pyogenes. A hybrid gene consisting of the promoter and signal sequence fused to the region encoding the mature sequence of the slo gene was constructed to secrete SLO in Bacillus subtilis. To increase secretion of SLO into the culture supernatant, several SLO expression vectors containing various combinations of promoters and pre-pro sequences were constructed. B. subtilis harboring pPA consisting of the P-43 promoter and the coding sequence of the pre region of the alkaline protease gene that was fused to the pro-mature region of the slo gene secreted SLO into media. The degree of hemolytic activity was found to be about 40-fold higher in the geneticaly engineered B. subtilis strain than that of S. pyogenes. Recombinant SLO was reacted with patients' sera infected by group A streptococci.