Effect of abiotic stress conditions on expression of the Lactobacillus brevis IOEB 9809 tyrosine decarboxylase and agmatine deiminase genes.

Lactobacillus brevis IOEB 9809, isolated from red wine, is able to produce both tyramine and putrescine. Using a real-time quantitative reverse transription PCR (qRT-PCR) we analyzed the relative expression of L. brevis IOEB 9809 tdc and aguA1 genes, encoding, respectively, a tyrosine decarboxylase and an agmatine deiminase enzyme. Relative gene expression was monitored either during the different growth phases under optimal conditions or under abiotic stress commonly found in wine. The tdc and aguA1 specific cDNA were amplified with specific primers. Our results indicate that tdc and aguA1 genes are differently expressed during the different growth phases and transiently induced by ethanol (12% v/v) and acidic stresses (pH 3.2 and 5.0).