Etude de la constitution lipidique des membranes de bactéries lactiques utilisées en vinification

Abstract

Les lipides extraits des membranes de bactéries lactiques du vin sont séparés par chromatographie sur couche mince en phospholipides, glycolipides et lipides neutres. Le pourcentage de répartition de chaque classe varie, non seulement en fonction des souches, mais aussi selon leurs conditions de culture.

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Lactic and bacteria of wines are inhibited in fermenting must. Éthanol, fatty acids and other unknow yeast metabolites are responsible for the loss of viability and malolactic activity. Prior results suggest that they induce an alteration of the plasma membrane. Owing to their nature, we assume the lipid constituants to be the target of the inhibitors. So, we have undertaken the study of the membrane lipids of two strains, L. plantarum and L. oenos.

After extraction, the samples are analysed by HPTLC. Comparing the strains, the patterns reveal small differences in the distribution of phospholipids, glycolipids and neutral lipids.

Some culture factors were investigated for their influence. Within the cell cycle, the distribution of the various classes changes according to the period of incubation. If ethanol is added in the culture medium, neutral lipids decrease by 25 to 50 per cent and glycolipids increase by 30 per cent depending on the age of the culture. Phospholipids remain quite constant.

Further researchs are in progress to test the influence of others factors. These results might explain the loss of viability of the bacteria varies when they are added to wine, as well as the variable response to yeast antagonism according to the strains.