Phage cocktail preparation and microencapsulation. Flasks containing 100 ml
of nutrient broth were inoculated with 320 l of log-phase Salmonella enterica
serovar Typhimurium organisms and incubated for 4 h at 37°C with shaking.
Individual flasks were then inoculated with 1 ml of phage stock (109 to 1010
PFU/ml) and incubated overnight at 37°C with shaking. Overnight cultures were
centrifuged (1,000 g for 10 min), filtered (0.2-m filter), and treated with
chloroform (1:100) as previously described. Each phage isolate was grown individually.
The treatment cocktail was a combination of equal volumes of all 14
wild-type phages along with anti-Salmonella phage Felix O1, which was previously
shown to have in vivo anti-Salmonella activity (16).