Purification of B. subtilis spores was conducted in DSM using the exhaustion method. The rVP28-bs and rVP28-bs-gfp suspension containing 108 spores was coated with 0.01 g of commercial pellets, respectively, as previously described. The B. subtilis WB600 strain was also coated for the control group. The prepared food pellets were stores at 4°c until further use.