Acid challenge of PA adapted and unadapted S. Enteritidis. Graph illustrates the percent survival of PA adapted, NaCl adapted, and unadapted S. Enteritidis LK5 cultures. All cultures were adapted for 16 hours and subsequently challenged over a three hour period to a highly acidic medium (pH 3.0). Acid resistance was determined by calculating the overall percent survival of each culture following acid exposure. Presented data is the average of three independent trials. Standard error is represented by error bars. Conditions that are significantly different from the unadapted condition with respect to acid resistance are indicated with an asterisk.