Coral-Associated Bacteria as a Promising Antibiofilm Agent against Methicillin-Resistant and -Susceptible Staphylococcus aureus Biofilms

The current study deals with the evaluation of two coral-associated bacterial (CAB) extracts to inhibit the biofilm synthesis in vitro as well as the virulence production like hemolysin and exopolysaccharide (EPS), and also to assess their ability to modify the adhesion properties, that is cell surface hydrophobicity (CSH) of methicillin-resistant (MRSA) and -susceptible Staphylococcus aureus (MSSA). Out of nine CAB screened, the ethyl acetate extract of CAB-E2 (Bacillus firmus) and CAB-E4 (Vibrio parahemolyticus) have shown excellent antibiofilm activity against S. aureus. CAB-E2 reduced the production of EPS (57-79%) and hemolysin (43-70%), which ultimately resulted in the significant inhibition of biofilms (80-87%) formed by both MRSA and MSSA. Similarly, CAB-E4 was also found to decrease the production of EPS (43-57%), hemolysin (43-57%) and biofilms (80-85%) of test pathogens. CLSM analysis also proved the antibiofilm efficacy of CAB extracts. Furthermore, the CAB extracts strongly decreased the CSH of S. aureus. Additionally, FT-IR analysis of S. aureus treated with CAB extracts evidenced the reduction in cellular components compared to their respective controls. Thus, the present study reports for the first time, B. firmus-a coral-associated bacterium, as a promising source of antibiofilm agent against the recalcitrant biofilms formed by multidrug resistant S. aureus.