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Diversités moléculaire et phénotypique de souches autochtones oenologiques de Saccharomyces cerevisiae isolées au Liban.

Abstract : We explored in this study the biodiversity of the fermenting indigenous Lebanese flora
of Saccharomyces cerevisiae by collecting samples of natural fermentations of grape musts
from various localities dispersed within the Lebanese territory. A great molecular diversity of
the Lebanese flora was found in the natural fermentations, as well as in the wineries as a
whole and between different geographic localities. However, cases of dominance and
perenniallity were also recorded in wineries. Besides, fermentations in the same wineries
seemed to involve lineages of related strains. Relatedness of strains was also seen in narrow
geographical areas while it was lost as the areas enlarged. Despite its diversity, the Lebanese
flora could nevertheless be interrelated, which property was observed when this flora was
compared to other oenological floras of diverse origins. Finally, it seemed that the effect of
the thriving media was greater on the lineages of fermenting floras than the effect of the
geographical distance.
We also evaluated the usefulness of the molecular typing methods used for assessing the
biodiversity of the S. cerevisiae floras. Two of them, interdelta fingerprinting and
microsatellites analysis, were previously developed, while we tested a new method, the
MLST. The first two methods were very useful for typing due to the great variability of their
markers and thus to their great discriminatory power, while MLST showed a lower
discriminatory power. But our MLST scheme could probably be improved by using more
variable loci. MLST was nonetheless more useful in inferring strains relatedness, especially
for poorly related isolates.
We further examined the phenotypic diversity that accompanies the molecular one in
order to initiate a selection scheme for some oenological strains and also to verify the
correspondence between the molecular and the phenotypic diversity. The studied strains of S.
cerevisiae presented different fermenting capacities which could be exploited to push further
the selection scheme for potential commercial uses, in particular in the Lebanese winemaking
industry. On the other hand, a certain congruence between the molecular and the phenotypic
diversities was observed and it was mainly due to a correlation between high acetaldehyde
productions and particular molecular profiles. If this path is studied further, this congruence
might help predict acetaldehyde production for particular strains
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Submitted on : Monday, March 12, 2007 - 12:12:38 PM
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  • HAL Id : tel-00136103, version 1
  • PRODINRA : 251863

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Marie-José Ayoub. Diversités moléculaire et phénotypique de souches autochtones oenologiques de Saccharomyces cerevisiae isolées au Liban.. Biologie cellulaire. Institut national agronomique paris-grignon - INA P-G, 2006. Français. ⟨tel-00136103⟩

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