['Lactobacillus brevis IOEB 9809 is able to produce both tyramine and putrescine via tyrosine decarboxylase and agmatine deiminase enzymes, respectively, when cultured on synthetic media. The aims of this study were to assess the expression of L. brevis IOEB 9809 tdc and aguA1 genes, during wine fermentation and to evaluate the effect of substrate availability and pH on tdc and aguA1 expression, as well as on biogenic amine production and L. brevis viability.', 'The relative expression of L. brevis IOEB 9809 tdc and aguA1 genes was analysed in wine by quantitative real-time RT-PCR (qRT-PCR) during a period of incubation of 30 days. Cell viability, pH values, putrescine and tyramine concentration were monitored throughout the experiments.'] Does expression of Lactobacillus brevis IOEB 9809 tyrosine decarboxylase and agmatine deiminase genes in wine correlate with substrate availability?