RAPID MONITORING METHOD TO ASSESS EFFICACY OF SANITIZERS AGAINST PSEUDOMONAS-PUTIDA BIOFILMS

Biofilms of luminescent Pseudomonas putida were developed on rubber su rfaces by incubation in brain heart infusion (BHI) broth. Scanning ele ctron microscopy (SEM) and epifluorescence microscopy (EFM) were used to examine biofilm formation. To test the efficacy of two sanitizers c ommonly employed in dairy plants for CTP (cleaning in place) procedure s, a novel bioluminescence method and aerobic plating were used to enu merate cells. immediately after the sanitizer treatments an apparent 5 -log reduction of biofilm-associated cells was determined. However, wh en the samples were resuscitated for 18 h in BHI broth, high numbers o f cells were detected which reached levels close to those of nontreate d controls. The results demonstrated that neither sanitizer could comp letely eliminate biofilm-associated P. putida. The microbial biolumine scence method proved to be the best way for assessing effectiveness of sanitizers against microbial biofilms.