Thereafter, the cells were re-suspended in adjusted PBS (1 mL) with pH 2.5 or media-THIO (thioglycollate media) broth (37°C) for 3 h. Themedia-THIO broth was prepared by mixing MRS brothwith 0.3% (w/v) oxgall and 0.2% (w/v) sodium thiogly-collate (Sigma, St. Louis, MO, USA).