Influence of the food matrix on dual-species biofilm of Listeria monocytogenes and Pseudomonas fluorescens

In the food industry, the formation of biofilms results in serious microbial recontamination problem. This work aimed to study Listeria sp. obtained from sliced products and food handling surfaces, for the preparation of food of animal origin to be consumed cold. Listeria monocytogenes, Listeria innocua and Listeria seeligeri were detected. In the evaluation of antibiotic susceptibility, the isolates were sensitive to ampicillin and penicillin, which were the main antibiotics used in treatment. The isolates showed the ability to form biofilm in microplate, in stainless steel and polypropylene surfaces, with a variation of sessile cells between 4.29±0.23 and 7.03±0.01 log10 CFU cm-2 in TSBYE. This ability was also observed in food matrix composed of UHT whole milk in mono-species cultivation and in associated cultivation of L. monocytogenes with Pseudomonas fluorescens. The application of sanitizers peracetic acid and sodium hypochlorite revealed efficiency in the eradication of adhered cells and biofilms formed in stainless steel surfaces. Therefore, Listeria sp. showed to be persistent and able to form biofilm in mono-species cultivation or associated with P. fluorescens, under different conditions. Taking these aspects into account, the need for proper hygiene in the food production process is highlighted in order to avoid risks to the consumers health