DIFFERENTIATION OF VIABLE AND NONVIABLE BACTERIAL BIOFILMS USING ELECTROROTATION

A new technique for studying the properties of biofilms has been devel oped, based on the phenomenon of electrorotation. Biofilms of Klebsiel la rubiacearum were formed on the surfaces of 6 mu m diameter polystyr ene beads, and the presence of such films was found to alter their ele ctrorotation spectra. The effects of adding a biocide (polyhexanide) t o the surrounding aqueous medium was also investigated. The dielectric properties of the beads with biofilms, before and after biocide treat ment, were interpreted from the electrorotation spectra using modellin g methods that have been well tested for other heterogeneous biologica l systems. The technique is of value in understanding the physico-chem ical properties of biofilms and can be adapted for monitoring the pres ence of toxic chemicals and for testing the activity of biocides again st biofilms.