]. In brief, freshly prepared MRS broth was supplemented with 0.30% oxigall (Sigma, MO, USA) as a bile salt. Water-soluble cholesterol (polyoxyethylene cholesteryl sebacate) was filter-sterilized and added to the broth at a final concentration of 200 to 300 µg/mL, inoculated with each strain and incubated anaerobically at 37 °C for 20 h.