THESE Maryse Bonnin Jusserand - Université de Bourgogne

Résultats
(Strahinic et al, 2009), and that proteolytically active strains can have another kind of
extracellular proteinase(s). Our result supports the view that peptides are hydrolyzed in the
extracellular medium and the released tyrosine is then transformed in tyramine via the
tyrosine permease and tyrosine decarboxylase system. However, it could not be excluded that
peptides are hydrolyzed inside or outside the cell. One can imagine that tyrosine obtained
from extracellular peptidases could be exchanged with tyramine that has been formed inside
the cell after decarboxylation of tyrosine derived from intracellular peptide hydrolysis.
However this mechanism has never been shown before whatever the bacteria.
Conclusion
This study demonstrates for the first time that peptide containing precursors of biogenic
amines could be used by bacteria to produce BA. In fact, peptides are another source of BA
precursors which are breakdown in AA in the extracellular medium. The hydrolysis outside
the cell is a simple way to obtain free AA for the metabolic needs. Indeed peptides transport
has an important energetic cost for the cell and required the hydrolysis of ATP (Kunji et al,
1996).
This study is of technological interest, since most of oenological practices aimed to enrich
wine in nutrients to allow the best performance of yeasts and lactic acid bacteria, and to
improve wine quality. That is why the influence of nitrogen sources on biogenic amines
production has been largely reported on the literature. Indeed the presence of fine yeasts lees
increase BA production, because of the released of a wide range of nitrogen precursors
(Marques et al, 2008). Moreover musts are sometimes nitrogen-supplemented to ensure a
good alcoholic fermentation by yeasts because nitrogen, and especially yeast assimilable
nitrogen, is the limited factor for yeasts development (Bely et al, 1991; Bach et al, 2010).
Nutritive supplements, like yeast autolysates composed of amino acids and proteins among
others, are added to must in order to activate alcoholic fermentation. It has been shown that
after malolactic fermentation in the wine from the supplemented must, a greater concentration
of biogenic amines was found (Gonzales Marco et al, 2006). Therefore since LAB are able to
produce biogenic amines from amino acids and directly from peptides, oenological practices
to ensure good development of alcoholic fermentation and malolactic fermentation, have to be
carefully monitored.
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