Fig 6. Functional link between stringent response and oxidative stress.

A. Strain HG001 and derivatives were grown with shaking aerobically or anaerobically to OD₆₀₀ = 0.3 and treated for 30 min without or with 0.1 μg/ml ATc (mutant with inducible rel-Syn). For Northern blot analysis, RNA was hybridized with digoxigenin-labelled probes specific for ftnA, dps, psm or agrA. The 16S rRNA detected in ethidium bromide-stained gels is indicated as a loading control in the bottom lane. B WT, (pp)pGpp⁰, ΔrelPQ and rel-Syn mutants were diluted from overnight culture to an OD = 0.1, challenged with different H₂O₂ concentrations, and growth was monitored over time.