Chapter 11 - Strategies based on microbial enzymes and surface-active compounds entrapped in liposomes for bacterial biofilm control

Abstract

Biofilms are complex microbial communities consisting of microcolonies embedded in their own microbial-originated matrix of protective and adhesive extracellular polymeric substances (EPSs), which are mainly polysaccharides, lipids, and proteins. Biofilm cells show greater resistance to environmental challenges including biocides, than their planktonic counterparts, mainly by polymeric matrix barrier formation. Conventional interventions with antimicrobials to eradicate biofilms are frequently ineffective. The resistance mechanisms of sessile cells to antimicrobial agents are complex and vary among biofilms in different stages. In recent years, novel antibiofilm strategies have been proposed and tested, as the use of microbial hydrolytic enzymes and surface actives compounds, free or entrapped in liposomes. These biomolecules can be effective in preventing adhesion to surfaces, bacterial differentiation, and matrix elimination by enzymes. Biosurfactants may prevent or delay the formation of biofilms on medical devices due to their interfacial and/or antimicrobial properties. Furthermore, liposomes, being similar in composition to microbial cell membranes, are readily incorporated into the biofilm. Once inside the biofilms, liposomes may undergo disintegration, resulting in release of the biocide or enzyme, and accumulation of the drug at the biofilm interface. In this review, potential strategies to control biofilms based on enzymes and biosurfactants free or entrapped in liposomes are discussed.