Acta Univ. Agric. Silvic. Mendelianae Brun. 2009, 57, 49-56
Published online 2014-10-10

Study of enterococci during cheese manufacture and ripening and evaluation of their role in tyramine production

Radka Burdychová

Ústav technologie potravin, Mendelova zemědělská a lesnická univerzita v Brně, Zemědělská 1, 613 00 Brno, Česká republika

The aim of this study was isolation, identification and characterization of bacteria of the genus Enterococcus from Duch-type semi-hard cheese during manufacture and ripening. Cheese samples from two different producers (I and II) were used at the production day and after 30, 90 and 176 days of ripening.
Altogether 361 suspected enterococci isolates were obtained from cheese samples during 7 month of ripening. Using genus-specific PCR, 285 isolates were identified as the members of the genus Enterococcus. The identification of five Enterococcus species was performed by PCR using species-specific primers. Among 165 Enterococcus spp. isolates of producer I, 81 isolates were classified as E. faecium, 39 as E. durans, 21 as E. faecalis, 19 as E. casseliflavus and 3 as E. hirae, and 2 isolates were not classified into species. Enterococci species among isolates of producer II were as follows: 52 isolates of E. faecium, 38 of E. faecalis, 14 of E. durans, 12 of E. casseliflavus, 3 of E. hirae and 1 was not classified into species. E. faecium was found to be the dominating species in all cheese samples. The gene coding for tyrosine decarboxylase was detected in 10 enterococci isolates of producer I and in 5 enterococci isolates of producer II. Production of biogenic amine tyramine was confirmed in all these isolates, which were of E. faecium, E. faecalis and E. durans species. It was confirmed that these species are important for tyramine production. There is the relationship between tyramine production and counts of E. faecium, E. faecalis and E. durans. No tyramine production was observed in isolates of E. casseliflavus or E. hirae species.


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