Polysaccharases in Biofilms — Sources — Action — Consequences!

Abstract

As such a large proportion of the structure of biofilms is composed of polysaccharides secreted by the constituent micro-organisms, the presence of enzymes (polysaccharases) acting on these polymers will inevitably have a very marked effect on the structure and on the integrity of the biofilm. It is also possible that glycosidases capable of cleaving exposed terminal monosaccharide residues may modify both polysaccharides and glycoproteins present in biofilms. Enzymes will derive from a variety of sources and may well differ considerably in their effects. It has also to be remembered that in multi-species biofilms, the collective action of several different enzymes may result in the degradation or alteration of polysaccharides which are resistant to discrete enzymes. Thus, the growth of different enzyme-secreting species in close proximity with intimate cell:cell contact may permit synergistic action of the enzyme mixture within the confines of the biofilm. The effects of polysaccharases may well be moderated if a mixture of polysaccharides is present and removal of one polymer leaves others with similar physical properties intact. The presence of other chemical compounds absorbed to the polysaccharides may also have a moderating influence on enzyme action. Thus simultaneous release of biosurfactants could well affect enzyme activity either positively (enhancing degradation) or negatively (inhibiting destruction of the substrate).