FIG. 2.

Bacterial growth (A) and penicillin-induced killing (B) monitored by viable counts and quantitative PCR of 16S rRNA genes. (A) Both viable counts and numbers of rRNA gene copies increased in parallel and stabilized in the stationary phase (data shown are for the parent S. gordonii strain). (B) After penicillin addition, viable counts decreased in the parent strain while remaining stable in the Tol1 mutant. Yet, quantitative PCR of rRNA genes remained steady for both organisms. Details and experimental reproducibility are described in the legend for Fig. 1.