Isolation and characterization of alkaline protease-deficient mutants of Pseudomonas aeruginosa in vitro and in a mouse eye model.

Mutants of Pseudomonas aeruginosa are described which are markedly deficient in alkaline protease production. Characterization of these mutants in vitro suggests that the mutations in two of these strains are specific for alkaline protease production. Examination of these mutants in a mouse eye model demonstrates that alkaline protease is required for the establishment of corneal infections with P. aeruginosa PA103. Mutants deficient in alkaline protease production could not colonize traumatized cornea and did not produce the corneal damage characteristic of infection by the parental strain. Addition of subdamaging amounts of alkaline protease to eyes infected with the protease-deficient mutants resulted in infections which were indistinguishable from infections caused by the parental strain.