Effect of an enzymatic treatment on the removal of mature Listeria monocytogenes biofilms: A quantitative and qualitative study

Biofilms increase the probability of microorganism survival and potentiate subsequent food product cross-contamination. The search for alternatives capable of eliminating the matrix produced by these communities, and accessing to the cells that made them up, is of real interest. This study aimed to evaluate the effectiveness of an enzymatic product on the detachment of mature Listeria monocytogenes biofilms formed on stainless steel surfaces. Biofilms were produced for one week with washes and replenishment of nutrients and, when formed, enzymatic treatments were applied at 50 °C for 20 min. The cells remaining on the surface were quantified by TEMPO and qualitatively evaluated by direct epifluorescent microscopy. The results showed that the maximum reduction obtained was approximately 6.9 log CFU/cm² for the strain L. monocytogenes 5672, with a mature biofilm removal between of 85–99% for the different L. monocytogenes strains. Furthermore, the results showed that the detachment of mature biofilms may be directly related to the strain of L. monocytogenes, which could be because some strains can generate structures with a more robust matrix, making their detachment more difficult. Enzymatic cleaning treatment could be exploited as a potent technology to combat mature biofilms in the food industry.