Abstract
Aim Among 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.
Methods and Results Microtitre plate based biofilm assay showed that 2 μg/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 μg/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.
Conclusion Proteinase 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.
Significance of the study The 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.
