In the broth culture inhibition assay, 5 (29%) and 10 (53%) out of
the 17 probiotic strains showed inhibitory activity against
C. perfringens and C. difficile, respectively (Table 1). Inhibition was
only observed when the supernatant was not neutralized. When
MRS broth at pH 3.9 was used as the inoculum, growth of
C. perfringens and C. difficile was reduced by 7 and 22.5% compared
to MRS at pH 6.8. Also this assay was shown to be reproducible with
the same probiotics showing inhibitory activity against the clostridial
species in both assays