Relevant strains were
incubated at 37
C for 24 h in under anaerobic conditions in a MRS
medium. The cultures were centrifuged at 10 000 g for 10 min, after
which time the supernatant was drawn into an injector and passed
through a filter with 0.20 mm pore (Millipore, Molsheim, France)
diameter. Separately, indicator microorganisms were activated and
0.5 McF of bacterial suspension was inoculated into Muller Hinton
agar (Merck, Germany).