Abstract

. Phyllis Molobela *, T. Eugene Cloete and Mervyn Beukes

Removal of biofilms is difficult. In industrial settings, both the inactivation and removal of biofilms are of huge concern. If only disinfection without the removal of attached biofilms occurs, the inactivated biofilm cells may provide an ideal environment for further adhesion and growth, resulting in a complex matrix. Microbial resistance to biocides and their negative environmental impact are the main reasons for finding alternative biofilm control strategies. Enzymes may offer such an alternative. The objective of this study was to determine the effect of commercial proteases and amylases on biofilms formed by Pseudomonas fluorescens. Biofilms were grown in diluted medium containing glass wool used as the attachment surface. Extracellular polymeric substances (EPS) were extracted and EPS composition was determined. Protease (savinase, everlase and polarzyme) and amylase (Amyloglucosidase and Bacterial Amylase Novo) activity was tested on both biofilms and on extracted EPS. After testing enzymes, biofilm integrity was evaluated by scanning electron microscopy. EPS composition consisted predominantly of proteins. Everlase and Savinase were the most effective enzymatic treatments on removing biofilms and degrading the EPS