Isolation and characterization of protease-deficient mutants of vibrio cholerae.

Mutants of Vibrio cholerae that were deficient in protease production were isolated by picking clones form gelatin or casein plates which showed reduced zones of proteolysis. All mutants showed reduced ability to degrade complex proteins (casein and gelatin), and those tested were deficient in ability to degrade chicken egg ovomucin. Some of the mutants demonstrated a decrease in neuraminidase activity. Almost all mutants showed a dramatic loss of virulence in the infant mouse, although toxin was still produced. A partial revertant, to protease-proficient, demonstrated a simultaneous increase in neuraminidase activity and also an increase in mouse virulence. The strains described had a variety of phenotypes.