Relative expression of tdc (A) and aguA1 (B) genes. Total RNAs were extracted at mid-exponential phase prior treatment (untreated) and after saliva plus gastric stress at either pH 5.0 (G pH 5.0) or pH 4.1 (G pH 4.1), in presence of 4.38 mM agmatine, 10 mM tyrosine or both, or in their absence. mRNA levels were quantified as n-fold differences by comparing to RNA samples from their respective unstressed cultures (mRNA value=1). Relative levels of expression in absence of BA-precursors for untreated/G pH 5.0/G pH 4.1 were 1/0.7/0.4 in (A) and 1/0.6/0.3 in (B). Each experiment was performed in triplicate. Vertical bars represent the standard deviation. Differences were assessed by Anova test. Different superscript letters associated with values of either tyrDC or aguA1 mRNA levels indicate statistically significant differences (P < 0.05).
Russo et al. BMC Microbiology 2012 12:247 doi:10.1186/1471-2180-12-247