Nutrition and Food Chemistry

Biography

Biography: Luisa Brito

Abstract

Listeria monocytogenes is foodborne pathogenic bacteria that cause human listeriosis, a severe zoonotic disease, with high morbility, hospitalization and lethality rates in vulnerable populations. L. monocytogenes is known to be a concern in the production of cheese. The production environment is often pointed out as a possible transmission route of the microorganism and the persistence of some molecular types has been described. Field experiments under actual dairy processing conditions are welcomed by the industry and the use of an appropriate non-pathogenic surrogate for L. monocytogenes in this kind of experiments is necessary. The present study aimed to investigate whether L. innocua may be used as a surrogate of L. monocytogenes in dairy processing environment experiments. 10 persistent and non-persistent isolates of L. innocuaand L. monocytogenes collected from cheese processing plants were used to compare biofilm-forming ability and biofilm susceptibility to two in use hydrogen peroxide (HP) based disinfectants. No significant differences in biofilm-forming ability by these two species was observed (P>0.05). In a similar way, the susceptibility to HP disinfectants of the L. monocytogenes and L. innocua biofilms formed by persistent and non-persistent isolates, grown in clean and in dirty conditions, showed no significant differences (P>0.05). By PCA an initial 10-dimensional space (10 variables) was reduced to a plane F1F2 defined by the two first principal components. The projection of the different isolates in this plane showed that they could be clustered into two major groups; both include isolates from the two species (Fig.1). This study proved the suitability of L. innocua as an indicator of L. monocytogenes in Listeria control programs and as a surrogate in field experiments aiming to clarify the factors that contribute to L.monocytogenes persistent colonization of some cheese processing plants.