Figure 1. SR inactivation impairs starvation-induced, stationary phase, and biofilm antibiotic tolerance.
A. Detection of (p)ppGpp by thin layer chromatography. The E.coli relA+ strain expresses an inducible relA.
B. Growth curves of wild type (➄) and ΔrelA spoT (➉) strains, with and without SHX treatment.
C. Ofloxacin tolerance of log-phase bacteria following SHX-induced starvation. Error bars indicate SD. P ≤0.001 (*) versus wild type.
D. Ofloxacin tolerance of stationary-phase wild-type (➄), ΔrelA spoT (➉) and ΔrelA spoT +SR (➂) strains. Error bars indicate SD. P ≤0.05 (*) or ≤0.001 (**) versus wild type.
E. Antibiotic killing of biofilms treated with ofloxacin (30 µg/mL), meropenem (300 µg/mL), colistin (300 µg/mL) and gentamicin (50 µg/mL). Error bars indicate SD. P ≤0.0005 (*) or ≤0.05 (**) versus wild type.
F. Rates of protein and DNA synthesis in biofilms measured by S35-methionine and H3-adenine incorporation. Error bars indicate SD. P ≤0.05 (*) versus wild type.
