Fig.
8. The growth transition into the stationary phase leads to theΔybeX phenotype. (A ) A scheme of the experimental setup
is given. A single colony was inoculated into MOPS minimal medium
supplemented with 10 mM MgCl2 and grown overnight at
37°C. The next day, saturated cultures were washed three times to remove
residual magnesium and regrown in 10 µM MgCl2-containing
MOPS. Aliquots for plating on LB agar were taken at 2, 3, 4 and 5.5
hours. The LB agar plates either contained or did not contain
antibiotics, as shown on panels D and E, and they were incubated
overnight at 37°C or 42°C. (B ) The growth of the wild-type and
the ΔybeX strains was monitored at an optical density of 600 nm
in MOPS minimal medium supplemented with 10 µM MgCl2 and
0.5% glucose. The mean optical densities of three biological replicates
are shown with 95% CI-s. (C ) Dot spot experiments were
conducted as in Fig. 7A, and the cells were collected from indicated
time points, as in panel B. The ΔybeX cells differed from
wild-type in growth phenotype only when collected for the outgrowth spot
assay at the 5.5h time point. (D) When the outgrowth spot assay
plates contained tetracycline, erythromycin or chloramphenicol (at
sub-MIC concentrations listed in Materials and Methods), severe growth
inhibition was observed at the 5.5h time point.