Quantification of Extracellular–Polymeric Substances (EPS) Excreted by Foodborne Pathogen Salmonella Enteritidis PT30 During Biofilm Formation on Stainless Steel at Two Different Temperatures

Salmonella spp. is a pathogen of concern in the food industry. This study evaluated the effect of temperature (10 °C and 37 °C) on the biofilm formation of S. Enteritidis PT30 on stainless steel up to 50 h, assessing the biofilm index (BI). The main extracellular polymeric substances (EPS) such as carbohydrates, proteins and eDNA were quantified. Scanning electron microscopy (SEM) was used to evaluate the biofilm formation. Results showed the effect of temperature on biofilm formation and EPS production. After 5 h at 37 °C the growth of planktonic and biofilm cells considerably increased (~7 log); however, the BI was higher for biofilms at 10 °C. Carbohydrates reached a maximum concentration after 15 h at 37 °C (65.49 μg/mL). The protein concentration reached a peak after 24 h regardless of the temperature. eDNA production was similar between the two temperatures (α = 0.05) and through the incubation time, ranging from 1.65 to 2.21 ng/μL. SEM images showed three-dimensional structures of the biofilm formed at 37 °C composed of cells, filaments, excreted EPS and a network of fibers. These results can help to understand the biofilm formation from this pathogen and develop effective interventions to break down these complex structures and effectively sanitize food contact surfaces.