Isolation and characterization of a lytic Salmonella Typhimurium-specific phage as a potential biofilm control agent

Abstract

This study aimed to characterize a lytic Salmonella Typhimurium-specific (ST) phage and its biofilm control capability against S. Typhimurium biofilm on polypropylene surface. ST phage was isolated, propagated, and purified from water used in a slaughterhouse. The morphology of ST phage was observed via transmission electron microscopy. Its bactericidal effect was evaluated by determining bacterial concentrations after the phage treatment at various multiplicities of infection (MOIs) of 0.01, 1.0, and 100. Once the biofilm was formed on the polypropylene tube after incubation at 37°C for 48 h, the phage was treated and its antibiofilm capability was determined using crystal violet staining and plate count method. The phage was isolated and purified at a final concentration of ∼11 log PFU/mL. It was identified as a myophage with an icosahedral head (∼104 nm) and contractile tail (∼90-115 nm). ST phage could significantly decrease S. Typhimurium population by ∼2.8 log CFU/mL at an MOI of 100. After incubation for 48 h, biofilm formation on polypropylene surface was confirmed with a bacterial population of ∼6.9 log CFU/cm2. After 1 h treatment with ST phage, the bacterial population in the biofilm was reduced by 2.8 log CFU/cm2. Therefore, these results suggest that lytic ST phage as a promising biofilm control agent for eradicating S. Typhimurium biofilm formed on food contact surfaces.