Protease-deficient Mutants of Pseudomonas aeruginosa: Pleiotropic Changes in Activity of Other Extracellular Enzymes

Mutants of Pseudomonas aeruginosa strain PAKS-1 which are defective in the formation of extracellular protease activity have been characterized. The mutants produced between approximately 1 and 25 % of the protease activity of the wild type and no strains completely lacking extracellular protease were found, even after repeated mutagen treatment. Most mutants also had changed activities of extracellular staphylolytic enzyme, lipase and lecithinase. Four of 13 mutants were unable to release alkaline phosphatase and staphylolytic enzyme into the medium in contrast to the wild type. Serotype, phage type and biochemical reactions were essentially unchanged. The results indicate that some of the mutations affected the cell envelope structure or function leading to decreased ability to release extracellular proteins, and that other mutations possibly affected a common regulatory mechanism for extracellular enzymes.