<i>Salmonella enterica</i> isolates from layer farm environments are able to form biofilm on eggshell surfaces

<p>This study examined the eggshell biofilm forming ability of <i>Salmonella enterica</i> isolates recovered from egg farms. Multicellular behaviour and biofilm production were examined at 22 and 37°C by Congo red morphology and the crystal violet staining assay. The results indicated that the biofilm forming behaviour of <i>Salmonella</i> isolates was dependent on temperature and associated with serovars. Significantly greater biofilm production was observed at 22°C compared with 37°C. The number of viable biofilm cells attached to eggshells after incubation for 48 h at 22°C was significantly influenced by serovar. Scanning electron microscopic examination revealed firm attachment of bacterial cells to the eggshell surface. The relative expression of <i>csg</i>D and <i>adr</i>A gene was significantly higher in eggshell biofilm cells of <i>S</i>. Mbandaka and <i>S</i>. Oranienburg. These findings demonstrate that <i>Salmonella</i> isolates are capable of forming biofilm on the eggshell surface and that this behaviour is influenced by temperature and serovar.</p