ABSTRACT
Biofilms are notoriously difficult to control by the use of conventional chemical agencies or antibiotics and can often survive on a surface through relatively harsh hygienic cleaning protocols (Characklis, 1990; Little et al., 1990; Holah et al., 1994). Much of this recalcitrance has been attributed to a reaction diffusion limitation to the passage of chemically reactive biocides such as peroxides, isothiazolones, and halogens, across the glycocalyx (De-Beer et al., 1994; Huang et al., 1995). The action of such agents has also been noted to change the visco-elastic properties of the glycocalyx, in some instances
firmly cementing the biofilms to the treated surface. This renders the cleansing of the surface more problematic and leaves residues that promote re-establishment of a new biofilm post-treatment. Other factors that contribute to the reduced susceptibility of the biofilm community relate to the much reduced growth rate displayed by deeply-seated cells brought about by nutrient-deprivation. This sub-population of cells may, in many instances, be regarded as metabolically dormant (Lewandowski et al., 1991; Fletcher, 1992; Mozes and Rouxhet, 1992). Slow-growing and dormant cells are co-incidentally less susceptible to the actions of most chemical antimicrobials and antibiotics (Costerton et al., 1987; Brown et al., 1990; Gilbert et al., 1990).
