Effect of cationic surfactants on biofilm removal and mechanical stability

Abstract

In this study, a methodology is proposed to evaluate the mechanical stability of biofilms, by using a stainless steel rotating device where biofilms formed by Pseudomonas fluorescens were allowed to grow for 7 days at 300 rmp. Those biofilms were afterwards submitted to the joined action of chemical agents and mechanical cleaning. Two cationic surfactants (cetyltrimethyl ammonium bromide - CTAB and benzalkonium chloride - BC) were the agents tested. Mechanical cleaning was performed by the variation of the rotation speeds of the rotating device. The following conclusions can be drawn: the biofilm has an inherent mechanical stability; the increase in the rotation speed increased the biofilm removal, but total biofilm removal was not found for the surfactants. BC promoted the increase in the biofilm mechanical stability while CTAB promoted the weakening in the biofilm mechanical stability. From this study, it can be stated that the chemical treatment is far from being a tool that induces massive biofilm detachment and even the synergistic chemical and mechanical treatment did not promoted total biofilm removal.