Isolation and characterization of tyramine-producing Enterococcus faecium strain from red wine.

Enterococcus faecium strains were isolated from red wines undergoing malolactic fermentation and identified by comparison of their 16S rDNA gene sequences with those included in the GenEMBL Databases. The tyrosine decarboxylase gene was identified in all the strains analysed by PC using gene-specific primers. Furthermore, the strain ability to produce tyramine was assayed in a syntetich media was and the biogenic amine produced was analysed by RP-HPLC. Survival of an E. faecium strain was also evaluted in microvinifications assays using two different musts with different ethanol concentrations (10% and 12% (v/v)) and the tyramine production was monitored during the vinification trials. Our results suggest that E. faecium strains isolated from wine are able to produce tyramine either in vitro or in vivo and that they are able to survive in wine after an acidic adaptation step.