THESE Maryse Bonnin Jusserand - Université de Bourgogne

Résultats
All fermented foods (dairy products, beer, wine, cider, soybean sauces, fermented sausages,
etc.) carry the risk of biogenic amine contamination (18, 17). High amounts of these
molecules can cause undesirable physiological effects and can negatively alter the
organoleptic properties of contaminated products (4). Indeed, the aromatic amines, histamine
and tyramine, are regarded as undesirable compounds because of the potential toxic effects
derived from their vasoactive and psychoactive properties (21).
There are two types of amino acid catabolic pathways that lead to biogenic amine formation.
The decarboxylation pathways involve only two proteins, a decarboxylase and a transporter
protein. The former converts the amino acid in the cytoplasm into the biogenic amine and
carbon dioxide; the latter is responsible for the uptake of the amino acid from the medium and
the excretion of the amine in an exchange process.
The physiological role of amino acid decarboxylative pathways in microorganisms is still
uncertain: amine accumulation is generally considered a defense mechanism used by bacteria
to counter an acidic environment (14, 1) but also a means to obtain metabolic energy through
an electrogenic amino acid/amine antiport system leading to the generation of proton motive
force (14). The latter function is particularly important in microorganisms that lack a
respiratory chain to generate high ATP yields, such as lactic acid bacteria (LAB) (9).
Among the predominant LAB associated with wine fermentation, Lactobacillus, Leuconostoc,
and Pediococcus genera have been shown to produce biogenic amines (16). Oenococcus oeni,
the bacterial species most commonly found in wines and most frequently associated with
malolactic fermentation (MLF), has been reported to produce histamine (3).
Regarding putrescine production, in silico analysis of the three Oenococcus oeni genomes
available did not reveal the presence of any odc homologs. Consistent with this, Granchi et al.
(6) did not detect any putrescine producer among the 42 Oenococcus oeni strains tested. In
contrast, Guerrini et al. (7) and Marcobal et al. (12) isolated Oenococcus oeni strains that did
produce putrescine. Moreover, Marcobal et al. (12) identified an odc gene encoding a 745-
amino-acid putative decarboxylase (ODC) (EC 4.1.1.17).
The biochemical characterization of ornithine decarboxylase has been poorly studied in
bacteria and especially in lactic acid bacteria (8). Despite the importance of biogenic amines
in fermented products, no studies have been conducted on lactic acid bacteria isolated from
this environment. Only one study has reported the biochemical properties of ODC in a
laboratory lactic acid bacterium, the collection strain Lactobacillus sp 30a previously isolated
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