Biofilm removal mediated by Salmonella phages from chicken-related sources

Salmonella and their biofilm formation are the primary bacterial causes of foodborne outbreaks and cross-contamination. The objective of the study was to investigate the potential of Salmonella phages as an alternative technology for biofilm removal. In this work, 21 Salmonella phages were isolated from a chicken farm and slaughter plant and the phage (CW1) with the broadest spectrum was characterized. Complete genome sequence analysis revealed that the genomes of phage CW1 is composed of 41763 bp with 58 open reading frames (ORFs) and a holin-endolysin system and it does not encode any virulence or lysogeny. A phage cocktail consisted of CW1 (with the broadest spectrum of 70.49 %) and CW11, M4 and M10 (with a high lytic activity of more than 67.11 %) was established. Treatment with the cocktail reduced the cells in the developing biofilm and mature biofilm by 0.79 lg(CFU/cm2) and 0.4 lg(CFU/cm2), respectively. More dead cells and scattered extracellular polymeric substances (EPS) were observed by confocal laser scanning microscopy and scanning electron microscopy. Raman analysis found that carbohydrates and proteins were the identification receptors for scattered EPS. This finding suggests that this phage cocktail has potential applications for the sterilization of Salmonella biofilm during meat processing.