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영어

Bacterial biofilms are associated with persistent infections due to their high resistance to antimicrobial agents. Hence, controlling pathogenic biofilm formation is important in bacteria-related diseases. Staphylococcus aureus is a versatile human pathogen and readily form biofilms on human tissues and diverse medical devices. Since S. aureus can be naturally found in multi-species communities, the supernatants of 29 bacteria have been screened to identify biofilm inhibitory components against S. aureus. The culture supernatant (1%, v/v) of Pseudomonas aeruginosa PAO1 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 S. aureus biofilms. Transcriptome analyses showed that the addition of P. aeruginosa supernatant induced the expression of endogenous protease genes (aur, clp, scpA, splA, and sspA) and other important regulatory genes (quorum-sensing agrA, hemolysin hla, and histidine protein kinase saeS). Additionally, the treatment of 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 to rapidly disperse its biofilm. This study proposes a possible acceleration model of protease-involved biofilm dispersal in S. aureus.