The cell suspension (108e109 CFU/mL) was mixed
(1:1) in 2 SES with 0.6% (w/v) pepsin. Samples were incubated
with agitation at 37 C. Gastric environment was reproduced by
progressive acidification (addition of 1 M HCl) from the initial pH
value of 5.0 to 4.1, 3.0, 2.1 and 1.8.