Commercial MRS Agar (Difco e Becton, Dickinson and Company,
Franklin Lakes, USA) was prepared according to manufacturer's
instructions. The rehydrated medium was autoclaved at 121 C for
15 min. For bile solution, 10 g bile (B3883 e SigmaeAldrich Co., St.
Louis, USA) was dissolved in 100 mL distilled water, and the solution
was autoclaved at 121 C for 15 min. Immediately before use,
1.5 mL bile solution was added to 100 mL MRS agar