Antibiotic inhibition of protease production by Pseudomonas aeruginosa

The effects of tetracycline, chloramphenicol and polymyxin B on growth and protease production by Pseudomonas aeruginosa were studied. Tetracycline inhibited protease production at concentrations much lower than those required to cause growth inhibition; the effect was not due to inhibition of protease activity by the antibiotic. In contrast, chloramphenicol and polymyxin B inhibted protease production in direct proportion to the inhibition of growth. Lysozyme-release experiments with washed tetracycline-treated cells indicated that the protease did not accumulate intracellularly. The protease-inhibiting effect of tetracycline might have therapeutic significance if it were found to occur in vivo.