Growth-phase-dependent acid tolerance in L.
monocytogenes. (a) Cultures were grown to either exponential
(เส้นสีแดง) or stationary (เส้นสีเขียวเข้ม; 24 h culture) phase. The pH was then
reduced to 3.0 with HCI and cell viability was measured a t the
time intervals shown. (b) Acid resistance measured throughout
growth. A culture of strain Scott A was set up and viable cell
counts were performed a t appropriate intervals in order to
monitor growth (เส้นสีเขียวอ่อน). Samples were also removed from the
culture throughout growth in order to assess acid resistance.
Viable cell counts were performed immediately before and
after an acid challenge a t pH 3.0 for 90 min and results are
presented as percentage survival (เส้นสีน้ำเงิน)