Seven protease-deficient mutants were isolated from Pseudomonas aeruginosa strain IFO 3455 which was mutagenized with nitrosoguanidine. Characterization of these mutants in vitro revealed that all mutants showed pleiotropic changes in the production of other extracellular substances. Among the mutants, two were chosen for a bacterial adherence test to Rabbit Cornea Cell Line (SIRC) cells. One mutant (IFO 3455-2) completely lost its protease activity. Another (IFO 3455-3) retained a low protease activity and was relatively similar to the parental strain with respect to extracellular products except for protease. Both mutants gave not a marked but a slight decrease of adherence as compared with the parental strain. This finding suggests that besides protease more factors are involved in the adhesion between P. aeruginosa and SIRC cells
