A loop sample of the strain from TSA was taken to prepare
the inoculum; it was grown in tripticasein-soy broth
(Merck, Mexico City, Mexico) previously acidified with
citric acid to reach pH 4. The inoculum was stored at 35°C.
Fresh inoculum was prepared daily to maintain the exponential
growth phase (about 109 CFU ml
1) (FDA, 2001).