Anti-Salmonella polyvinyl alcohol coating containing a virulent phage PBSE191 and its application on chicken eggshell

The use of antibiotics in the food industry is avoided due to the increase of antibiotic-resistant bacteria. Therefore, the bacteriophage is emerging as an alternative agent. Here, we characterized the Salmonella Enter-itidis phage PBSE191 and applied it to a polyvinyl alcohol (PVA) film. Transmission electron microscopic analysis revealed that it belonged to the Caudoviricetes class, with an icosahedral head and flexible tails. The phage showed rapid and strong lytic activity within 1 h. It was active against a broad range of Salmonella isolates, including six serotypes. In 25 min, 99 % of the initial population was adsorbed to the bacterial cell surface. The phage was also applied to 10 % (w/v) PVA films and coatings, which were then characterized in terms of phage stability and antibacterial performance, both in vitro and in foods. The phage remained stable in the 10 % (w/v) PVA solution containing 20 % (w/w, based on PVA weight) sorbitol (PVAS20), indicating that the phage was stable under dry conditions and strongly released in the polymer. Furthermore, significant bacterial cell reduction (2.0 x 105 CFU/film within 2 h) was observed in the phage-containing PVAS20 films. In addition, the PBSE191-containing PVAS20 coating on the chicken eggshell surface showed significant anti -Salmonella effi-ciency (about 2 log CFU reduction) within 24 h. Overall, the PBSE191 phage possesses a high potential as a biocontrol agent for use as an additive, or as an active antibacterial packaging to improve food safety against Salmonella contamination.

Automated summary

The use of antibiotics in the food industry is being replaced by bacteriophage due to the increase of antibiotic-resistant bacteria. In this study, the Salmonella Enter-itidis phage PBSE191 was characterized and applied to a polyvinyl alcohol (PVA) film. The phage showed rapid and strong lytic activity against a broad range of Salmonella isolates. Furthermore, it remained stable in a PVA solution and demonstrated antibacterial performance in both in vitro and in food tests.