Each microbial culture was transferred individually to 5 ml of deMan
Rogosa Sharpe medium (MRS broth, Difco) for lactic acid bacteria,
Tryptic soy broth (TSB, Difco) for other bacteria and Saboraud dextrose
broth (SDB, Difco) for yeasts. Cultures of bacteria and yeasts
were incubated at 37 and 30°C for 24 and 72 h, respectively. The
microbial cells were harvested by centrifugation at 3000 rpm for 15
min, washed twice and resuspended in 0.1% peptone water. Turbidity
was adjusted to match that of 5 McFarland standard (0.5 for
yeasts) to obtain a cell concentration of 10
7 CFU/m