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Figure 4 | BMC Microbiology

Figure 4

From: Extracellular DNA-induced antimicrobial peptide resistance in Salmonella enterica serovar Typhimurium

Figure 4

Expression of pmrH-lux in peg-adhered biofilms requires PhoPQ and PmrAB. (A) Gene expression was measured in plastic peg-adhered biofilms cultivated 18 hrs in NM2 media with 100 μM Mg2+, 100 μM Mg2+ then spiked with 10 mM Mg2+ for 4 hrs, 1 mM Mg2+ or 10 mM Mg2+. Values shown are the average of 8 replicates with the standard deviation of gene expression (CPS) normalized to biofilm biomass (CV). Values that differ significantly from the controls (100 μM Mg2) are marked with an asterisk (*, p < 0.05; ***, p < 0.001 by unpaired t test). (B) Under repressing levels of 1 mM Mg2+, pmrH-lux expression was measured in biofilms formed by 14028, phoPQ and ΔpmrAB strains. Values shown are the average of 8 replicates with the standard deviation of gene expression (CPS) normalized to biofilm biomass (CV). Values that differ significantly from the controls (14028) are marked with an asterisk (***, p < 0.001 by unpaired t test). (C) The normalized pmrH gene expression under inducing conditions (100 μM Mg2+) was divided by the normalized pmrH expression in repressing conditions (10 mM Mg2+) and shown as a fold induction value from either peg-adhered biofilms (black bars) or planktonic cultures (grey bars). Each experiment was repeated three times.

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