Compensatory Evolution of pbp Mutations Restores the Fitness Cost Imposed by β-Lactam Resistance in Streptococcus pneumoniae
Figure 4
Septal localization in pbp mutants.
Exponentially grown cells were stained with DAPI and fluorescent vancomycin (Fl-Van, which labels nascent peptidoglycan synthesis and strongly marks septal localization) and analysed by using an epifluorescence microscope (see Material and Methods). The pbp2b showed a septal accumulation in rod-like shaped cells, whereas the double (pbp2b pbp2x or pbp2b pbp1a) and the triple pbp mutants restored their septal localization. Representative images are shown from experiments that were repeated independently three times (bar scale, 1 µm).