Staphylococcus aureus Biofilm Removal by Targeting Biofilm-Associated Extracellular Proteins

AimAmong cell surface proteins, biofilm-associated protein promotes biofilm development in Staphylococcus aureus strains. Aim of this study was to investigate proteinase-mediated biofilm dispersion in different isolates of S. aureus.\n\nMethods and ResultsMicrotitre plate based biofilm assay showed that 2 g/mL proteinase K significantly inhibited biofilm development in bap-positive S. aureus V329 as well as other S. aureus strains, i.e. SA7, SA10, SA33, SA352 and but not in bap-mutant M556 and SA392 (a weak biofilm producing strain). However, proteinase K treatment on S. aureus planktonic cells showed that there was no inhibition of planktonic growth at any concentration of proteinase K when tested up to 32 g/mL. This observation ruled out the possibility of S. aureus biofilm inhibition by altering the cell viability. Proteinase K treatment upon 24 h old preformed biofilms showed an enhanced dispersion of bap-positive V329 and SA7, SA10, SA33 and SA352 biofilms, however, proteinase K did not affect the bap-mutant S. aureus M556 and SA392 biofilms. Biofilm compositions study before and after proteinase K treatment indicated that Bap might also be involved in eDNA retention in the biofilm matrix that aid in biofilm stability. When proteinase K was used in combination with antibiotics, a synergistic effect in antibiotic efficacy was observed against all biofilm forming S. aureus strains.\n\nConclusionProteinase K inhibited biofilms growth in S. aureus bovine mastitis isolates but did not affect their planktonic growth. An enhanced dispersion of preformed S. aureus biofilms was observed upon proteinase K treatment. Proteinase K treatment with antibiotics showed a synergistic effect against S. aureus biofilms.\n\nSignificance of the studyThe study suggests that dispersing S. aureus by protease can be of use while devising strategies against S. aureus biofilms. Proteinase K treatment has a wider scope for control of S. aureus biofilms.