Fig. 5. Acid tolerance of H. pylori. Acid tolerance of H. pylori at 20, 40, and 60 min in the
pH 4 buffer was assayed by mixing H. pylori CPY3401 with K. denitrificans NHP1,
K. denitrificans ATCC3394, and buffer alone. Percent survival of H. pylori CPY3401 at pH
4 condition in contrast to pH 7 condition was calculated by comparing the numbers of
colonies.