Acceleration of protease effect on S taphylococcus aureus biofilm dispersal

Bacterial biofilms are associated with the persistent infections because of their high tolerance to antimicrobial agents. Hence, controlling pathogenic biofilm formation is important in bacteria‐related diseases. S taphylococcus aureus is a versatile human pathogen that readily forms biofilms on human tissues and diverse medical devices. As S . aureus can be naturally found in multi‐species communities, the supernatants of 28 bacteria were screened to identify new biofilm inhibitory components against S . aureus . The culture supernatant (1%, v/v) of P seudomonas aeruginosa PAO 1 inhibited S . aureus biofilm formation more than 90% without affecting its planktonic cell growth. The P . aeruginosa supernatant contained a high protease activity, which both inhibited S . aureus biofilm formation and detached pre‐existing biofilms. An examination of 13 protease‐deficient P . aeruginosa mutants identified that LasB elastase is a major antibiofilm protease in P . aeruginosa against S . aureus . Transcriptional analyses showed that P . aeruginosa supernatant induced the expression of endogenous protease genes ( aur , clp , scpA , splA , and sspA ) and other regulatory genes ( agrA , hla , and saeS ). Additionally, exogenous proteinase K clearly enhanced the protease activity of S . aureus . Hence, S . aureus accelerated the expression of its own protease genes in the presence of exogenous protease, leading to the rapid dispersal of its biofilm.