Fig. 4

Expression of histidine decarboxylase (hdcA), histidine/histamine antiporter (hdcP), and proton/chloride antiporters (eriC/eriC2) in L. reuteri. cDNA was synthesized from RNA extracted from 24 h MRS cultures. Expression values are reported as fold changes in cycle threshold (Ct) using the 2^−ΔΔCt method [36]. In each assay, rpoB (RNA polymerase, β subunit) was used as the reference gene and the Ct difference between the gene of interest and the reference gene in the wild type strain was used as the reference condition for all comparisons. Data displayed as the mean Log₂ of the fold change value (−ΔΔCt), ± SEM. N = 6 biological replicates. One-way ANOVA with Dunnett’s multiple comparison test compared to WT. *P < 0.05, **P < 0.01, ***P < 0.001