Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

FP5

DECARBOXYLATE Sintesi della relazione

Project ID: QLK1-CT-2002-02388
Finanziato nell'ambito di: FP5-LIFE QUALITY
Paese: Spain

Prevalence of biogenic amines producing lactic acid bacteria in European and Argentinean cheeses and wine

93 Lactococcus lactis, 22 Enterococcus spp. and 74 Lactobacillus spp. strains isolated from Spanish traditional cheeses were screened by colorimetric methods to identify tyramine and histamina producers. Twenty two tyramine-producing strains were confirmed. Most of them (19) belong to Enterococcus genus, two were Lactobacillus curvatus and one Lb. brevis. Histamine is not as abundant in dairy products as tyramine, and in fact, the screening has not yielded any histamine producers. The results were confirmed by the PCR methods developed in this project.

More strains of lactic acid bacteria (LAB) isolated from different kind of European cheeses were tested to identify tyramine-producing and histamine-producing strains. A surprisingly large percentage (40%) of analysed strains were tyramine producers. A significant lower proportion (9%) were histamine producers.

An Argentinean collection of strains isolated from artisanal cheeses and dairy products was analysed for the production of biogenic amines. A total of 32 citrate fermenting LAB strains have been studied. Among the other 30 LAB, 26 showed to be tyramine producers and they were identified by biochemical and molecular methods as Enterococcus. Detection of the genes encoding the histidine and tyrosine decarboxylase has been performed using the PCR method developed in this project. The DNA of all the strains yielded the expected tdc amplicon and, none gave a positive result for detection of hdc gene.

These results indicate a high incidence of tyramine producer Enterococcus strains in cheeses from Europe and from Argentina.

Commercial starter cultures (7 Lactococcus lactis , 8 Streptococcus thermophilus , 3 Lactobacillus helveticus, 1 Brevibacterium casei and 1 undefined mesophilic) were also tested by colorimetric and ELISA methods for their ability to decarboxylate histidine. All the strains were found to be negative in terms of their ability to decarboxylate histidine in the conditions assayed.

63 Lb. hilgardii strains from different kind of wine were also analysed by colorimetric methods for their ability to produce tyramine and the results confirmed by PCR. 22 strains (34 %) were positive. Interestingly, these strains do not originate from the same type of wine. In contrast, they are disseminated in all types of wines (white, red, dry, sweet, with high ethanol level, from different regions). Moreover, any wine can contain tyramine producing and non-producing strains.

The qPCR assay developed in this project was used to analyse 264 wine samples collected in wineries of Bordeaux s area during winemaking at the end of the malolactic fermentation. The results showed that 98% of the wines contained histamine-producing bacteria; up to a concentration of 5.106/ml. Histamine producers were present at concentrations above 1000 cells/ml in more than 72% of the samples.

The population of histamine-producing bacteria can be more or less important at different locations.

However, there are places where the wines contain very variable quantities of histamine-producing bacteria. Consequently, it is not certain that their distribution is related to specific geographical sites. Differences of wine composition and winemaking practices have most likely an important impact on the content in histamine-producing cells.

Informazioni correlate

Contatto

Miguel A. ALVAREZ, (Group leader)
Tel.: +34-98-5892131
Fax: +34-98-5892233
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