C. Effects of pH on Fn survival. Wild type Fn 12230 (Fn) or its fadA deletion mutant US1 (∆fadA) grown to log or stationary phase were washed and incubated in PBS at pH7 or pH4 for 1 or 2 hours. The live bacterial counts at time 0 were designated as 100%, and those after 1 or 2 hrs of incubation were expressed relative to time 0. The results shown are the average of 5 (for log) or 4 (for stationary) independent experiments, each performed in triplicate. The error bars indicate SD. *p<0.05, ** p<0.01, ***p<0.001 (One-way ANOVA). 