Biofilm Formation by Chicken Meat Microbiota and Salmonella enterica in the Presence of Skin, Raw Meat, and Grilled Chicken Meat Residues

Biofilm formation by Salmonella enterica has been extensively studied; however, in the environment, most biofilms consist of a variety of different bacterial species. Therefore, this study aimed to evaluate the in vitro biofilm formation by nine S. enterica strains both individually and in mixed cultures with chicken meat microbiota (CMM) under different storage conditions using various chicken extracts. For the individual S. enterica strains and mixed cultures, a total of 54 treatments were examined. Each sample were introduced to different types of chicken extracts (from chicken skin, raw meat, and grilled meat, each with or without CMM) across three different temperature conditions (9, 14, and 25°C) and over different times (either 24, 48, and 72 h, or 5, 10, and 15 days). Biofilm formation was assessed using the method described by O’Toole, which involves staining the biofilm with crystal violet, dissolving the attached dye with acetic acid, and measuring the optical density. This quantification allows for the classification of biofilm formation as non-, weak, moderate, or strong biofilm producers. In general, in the absence of CMM, most strains (70.4%) did not form biofilms at 9°C, whereas weak biofilm production was observed at 14 and 25°C for 42.0 and 46.9% of the strains, respectively. In the presence of CMM, most treatments were classified as strong biofilm producers (79.4%). Interestingly, some mixed cultures exhibited lower biofilm formation compared to CMM alone, suggesting a potential for competitive interactions between them. These results underscore the importance of creating more realistic scenarios to simulate biofilm formation in chicken production and preparation.