Antibiofilm Effect of Subtilisin and Fungal EPS against the Biofilm of Brevundimonas faecalis BC1 Collected from Monumental Rock

Biofilms forming due to the growth of epilithic bacteria, cyanobacteria, and fungi on stone monuments (monumental rock) cause its biodeterioration and disfiguration. To investigate the possibility of controlling the biofilm growth on monumental rock surface, we studied biofilm formation by Brevundimonas faecalis strain BC1 isolated from monumental rock in microtiter plate wells in the presence of subtilisin, a popular antibiofilm enzyme, EPS solution from a fungal strain (Aspergillus niger FC1) growing on monumental rock, and a cocktail of subtilisin and the EPS solution. In this study, subtilisin at its minimum tested concentration (0.01 U/mL) showed a decrease in biofilm biomass of B. faecalis BC1 to 37.33% compared to the control variant. Likewise, the EPS solution of A. niger FC1 at its minimum concentration (1.25 mg/mL) decreased the biofilm biomass to 52.16% compared to the control. However, a cocktail of subtilisin (0.01 U/mL) and the EPS solution (1.25 mg/mL) showed a very significant decrease in the biofilm biomass to 24.5% compared to the control. This cocktail is suggested for biofilm control on monumental rock, considering its high antibiofilm activities because of its additive effect due to a protease enzyme, subtilisin and antibacterial activities of the EPS solution of a fungus growing on monumental rock.