[Characteristics of the protease activity of Vibrio cholerae strains and mutants with various biological properties].

The study of 65 V. cholerae strains and mutants revealed that protease activity was high in choleragenic strains and mostly low, sometimes even not manifested, in noncholeragenic strains. The use of inhibitors made it possible to determine three types of protease. Choleragenic strains were found to possess all three types of protease, while in noncholeragenic strains only protease of type 1 was detected in very rare cases. In noncholeragenic hemolytic strains and mutants protease of type 3 and in nonhemolytic strains protease of type 2 were mainly detected. Proteases of types 1 and 3 were thermolabile, and protease of type 2 was thermostable. Proteases of types 1 and 2 were found to be correlatively linked with the choleragenicity of V. cholerae and with a number of its properties which determine the pathogenicity of this infective agent.