Surveillance of the behaviour of pseudomonas fluorescens biofilms after ortho-phtalaldehyde disinfection

Abstract

A relatively novel antimicrobial agent, ortho-phtalaldehyde (OPA), was tested in the control of biofilms formed by Pseudomonas fluorescens on stainless steel surfaces. The toxic action of OPA was assessed by means of activity tests and dry weight of the biofilms. For comparative purposes, the activity of OPA against bacterial suspended cultures was also evaluated. The results showed that concentrations of OPA higher than 15 mg L-1 inactivate the planktonic populations while having a lower effect against the P. fluorecens biofilms. The inactivation of the biofilm was only attained with the higher OPA concentrations (50 and 100 mg L-1) and for longer exposure times (3 h). The application of OPA appears to cause little effect in the removal of biofilms from the metal slides since the amount of biofilm mass that remained on the surfaces, after biocide treatment, stills to be very high and representative. These results suggest the fact that, with OPA application, biofilms can be inactivated but stay attached to the surfaces, decreasing, by this way, the success of the chemical treatment.