All strains of LAB
stock cultures were stored at 20 C in MRS broth (Difco Laboratories,
Detroit, MI) containing 10% (v/v) glycerol whereas E. coli and
Listeria innocua were propagated in BHI broth and maintained as
frozen stocks at 20 C in BHI broth (Difco Laboratories, Detroit,
MI) containing 10% (v/v) glycerol.