Biofilm removal by low concentrations of hydrogen peroxide

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Abstract
A micro‐annular reactor (MAR) was developed for studying biofilm processes. It is simple to operate under pure culture conditions and allows easy, non‐invasive monitoring of biofilm accumulation. Two marine bacteria were investigated which formed biofilms under conditions of continuous flow and during batch growth in rich media. Exposure of biofilms to low levels of hydrogen peroxide (1–5 mM) and ferric ions (0·03–0·1 mM) led to their detachment and removal, even though the growth of free cells was not totally inhibited under these conditions, and new biofilms formed readily upon introducing fresh medium. Repeated treatments of the same biofilm with hydrogen peroxide resulted however, in progressively less biofilm removal. The results show that biofilm removal can be accomplished with hydrogen peroxide at levels well below those required for total disinfection and point to a mechanism where the extracellular biopolymer matrix is degraded rather than intracellular components.