Relative expression of: a) the tyramine transporter tyrP and b) the tyrosine decarboxylase tyrDC in L. plantarum IR BL0076 grown with free tyrosine or tyrosine-containing peptides. Expression was measured at three different OD600nm. Each value is the mean + − SD of three independent experiments. The difference between the values labeled a are significantly different, likewise those labeled b (ANOVA, p < 0.05). Significant differences between Free AA (medium 1) and Synthetic peptides (medium 2) media for each OD are indicated with an asterix.