Biofilms of Enterococcus faecalis and Enterococcus faecium isolated from the processing of ricotta and the control of these pathogens through cleaning and sanitization procedures

• The ideal biofilm formation temperature for E. faecalis was at 25 °C.
• The ideal biofilm formation temperature for E. faecium was at 39 °C.
• The anionic tensioactive cleaning step is extremely important for removing biofilms.
• The peracetic acid was capable of removing all biofilms under all conditions tested.
• The biguanide sanitizer was unable to remove any of the biofilms.

The biofilm formation of Enterococcus faecalis and Enterococcus faecium isolated from the processing of ricotta on stainless steel coupons was evaluated, and the effect of cleaning and sanitization procedures in the control of these biofilms was determined. The formation of biofilms was observed while varying the incubation temperature (7, 25 and 39 °C) and time (0, 1, 2, 4, 6 and 8 days). At 7 °C, the counts of E. faecalis and E. faecium were below 2 log10 CFU/cm2. For the temperatures of 25 and 39 °C, after 1 day, the counts of E. faecalis and E. faecium were 5.75 and 6.07 log10 CFU/cm2, respectively, which is characteristic of biofilm formation. The tested sanitation procedures a) acid-anionic tensioactive cleaning, b) anionic tensioactive cleaning + sanitizer and c) acid-anionic tensioactive cleaning + sanitizer were effective in removing the biofilms, reducing the counts to levels below 0.4 log10 CFU/cm2. The sanitizer biguanide was the least effective, and peracetic acid was the most effective. These studies revealed the ability of enterococci to form biofilms and the importance of the cleaning step and the type of sanitizer used in sanitation processes for the effective removal of biofilms.