The impact of potassium peroxymonosulphate and chlorinated cyanurates on biofilms of Stenotrophomonas maltophilia: effects on biofilm control, regrowth, and mechanical properties.

The activity of two chlorinated isocyanurates (NaDCC and TCCA) and peroxymonosulphate (OXONE) was evaluated against biofilms of Stenotrophomonas maltophilia, an emerging pathogen isolated from drinking water (DW), and for the prevention of biofilm regrowth. After disinfection of pre-formed 48 h-old biofilms, the culturability was reduced up to 7 log, with OXONE, TCCA, and NaDCC showing more efficiency than free chlorine against biofilms formed on stainless steel. The regrowth of biofilms previously exposed to OXONE was reduced by 5 and 4 log CFU cm^-2 in comparison to the unexposed biofilms and biofilms exposed to free chlorine, respectively. Rheometry analysis showed that biofilms presented properties of viscoelastic solid materials, regardless of the treatment. OXONE reduced the cohesiveness of the biofilm, given the significant decrease in the complex shear modulus (G*). AFM analysis revealed that biofilms had a fractured appearance and smaller bacterial aggregates dispersed throughout the surface after OXONE exposure than the control sample. In general, OXONE has been demonstrated to be a promising disinfectant to control DW biofilms, with a higher activity than chlorine. The results also show the impact of the biofilm mechanical properties on the efficacy of the disinfectants in biofilm control.