FIG 5.

Stress tolerance is attenuated in C. sakazakii in the absence of Hfq. (A) Survival of C. sakazakii strains harboring the pACYC184 control plasmid or a complementation plasmid, pHFQ, upon treatment with 100 mM H₂O₂ for 10 min. (B) Indirect catalase activities of strains treated with H₂O₂. 1, wild type (SK001); 2, Δhfq (SK005); 3, Δhfq harboring pHFQ (SK007). The bubbles indicate oxygen gas, produced by decomposition of H₂O₂. (C) qRT-PCR analysis of oxyR and katG expression levels. To obtain the expression level relative to the WT on the y axis, the mRNA level of each gene was divided by the mRNA level of the 16S rRNA. The mRNA expression values in strains SK005 and SK007 were further normalized to the transcription levels of the wild type. The bars represent means and SEM from independent experiments performed in triplicate. The data are representative of 3 independent experiments. The asterisks indicate significant differences (**, P < 0.05).