Effect of glycosidases and proteases on biofilms formed on black buna-N rubber

Proteolytic enzymes and a glycolytic enzyme used in dishwashing detergents and by the starch conversion industry were examined for their ability to remove bacteria attached to black buna-N rubber. Pure culture and mixed culture biofilms of Pseudomonas fluorescens and Listeria monocytogenes were treated with the proteolytic enzymes Purafect® (Genencor International), Durazym™, and Savinase® and the glycolytic enzyme Termamyl® (Novo Nordisk BioChem North America). Compared to controls, none of the enzyme treatments were able to significantly remove P. fluorescens cells adherent in pure culture (p>0.05). Durazym™, Purafect®, and Termamyl® did significantly reduce the number of adherent cells of L. monocytogenes grown in pure culture. Treatment with Purafect® reduced the number of attached cells of both P. fluorescens and L. monocytogenes when grown in mixed culture. Material which absorbs at 280 nm was released from both pure and mixed culture biofilms when all three proteolytic enzymes were used. No survivors remained after planktonic (free floating) cells of both P. fluorescens and L. monocytogenes were incubated with Purafect®. Reduction in overall numbers of P. fluorescens and L. monocytogenes attached in mixed culture by Purafect® appeared to involve a combination of release of proteinaceous material followed by bactericidal effects on exposed cells.