The starvation-stress response (SSR) of
Salmonella typhimurium encompasses the physiological changes that occur upon starvation for an essential nutrient, e.g. C-source. A subset of SSR genes, known as core SSR genes, are required for the long-term starvation survival of the bacteria. Four core SSR loci have been identified in
S. typhimuriumrpoSstiAstiB, and
stiC. Here we report that in
S. typhimurium C-starvation induced a greater and more sustainable cross-resistance to oxidative challenge (15 mM hydrogen peroxide (H
2O
2) for 40 min) than either N- or P-starvation. Of the four core SSR loci, only
rpoS and
stiC mutants exhibited a defective C-starvation-inducible cross-resistance to H
2O
2 challenge. Interestingly, (unadapted) log-phase
S. typhimurium rpoS and
stiA mutants were very sensitive to oxidative challenge. Based on this, we determined if these core SSR loci were important for H
2O
2 resistance developed during a 60 min adaptive exposure to 60 μM H
2O
2 (adapted cells). Both unadapted and adapted
rpoS and
stiA mutants were hypersensitive to a H
2O
2 challenge. In addition, a
stiB mutant exhibited normal adaptive resistance for the first 20 mins of H
2O
2 challenge but then rapidly lost viability, declining to a level of about 1.5% of the wild-type strain. The results of these experiments indicate that: (i) the
rpoS and
stiC loci are essential for the development of C-starvation-inducible cross-resistance to oxidative challenge, and (ii) the
rpoSstiA, and, in a delayed effect,
stiB loci are needed for H
2O
2-inducible adaptive resistance to oxidative challenge. Moreover, we found that both
stiA and
stiB are induced by a 60 μM H
2O
2 exposure, but only
stiA was regulated (repressed) by (reduced form) OxyR.
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