The selected strains were stored in PDA slant tubes at +4[degrees]C and in sporal solution in Eppendorf tubes containing Potato Dextrose Broth (PDB) with 25% glycerol at "20[degrees]C.
After the solidification of the culture medium, one sterile disk was deposited in the center of the plate and then saturated with 10[micro]l of sporal suspension ([10.sup.6] spores/ml).
This recovery rate could be underestimated as sporal germination and the growth of thermo-resistant Bacillus and Lactobacillus may mask the presence of Listeria spp.