Observations on the role of the caseinase enzyme in the pathogenesis of furunculosis

The role of the caseinase extracellular enzyme in the pathogenesis of furunculosis was investigated. Natural and mutant strains of Aeromonas salmonicida which were unable, or limited, in their ability to produce this enzyme were studied. The virulence of the mutant strains of A. salmonicida was not significantly reduced by the lack of extracellular caseinase production. Furthermore, there was no difference in the toxicity of extracellular products produced by these mutant strains and the wild‐type A. salmonicida strain studied. It is reasonable to assume from these results that the caseinase enzyme has no major role in the pathogenesis of A. salmonicida infections.