Le TGV-Atlantique : entre récession et concurrence

Le TGV véhicule bien des images. Train des Parisiens ou de la décentralisation ? Vitesse démocratisée ou tarifs élevés ? Train d'affaires ou service public ? Le TGV transporte d'abord des voyageurs. Qui sont-ils ? Que font-ils ? Quelles sont leurs spécificités par rapport aux voyageurs utilisant un autre moyen de transports ? Sont-ils différents de ceux qui voyageaient avant sa mise en service ? En d'autres termes, quelles transformations de la mobilité tant professionnelle que personnelle peuvent-elles être reliées à la mise en service du TGV ?Pour répondre à ces questions, une enquête coordonnée sur les trois modes de transport (autoroute, avion, train) a été réalisée à l'initiative de l'Observatoire Economique et Statistique des Transports par le Laboratoire d'Economie des Transport en 1989 et en 1993 autour du TGV-Atlantique. Cette enquête, intervenue juste avant et quatre ans après la mise en service du TGV-Atlantique, a permis de recueillir 18.000 questionnaires portant sur l'ensemble des parcours Province-Paris concernés par la nouvelle offre. Cette synthèse des résultats permet de mieux comprendre comment les déplacement professionnels, les déplacements domicile-travail, les déplacements personnels ainsi que les relations entre l'Ile-de-France et les principales agglomérations de la façade atlantique de la France se sont modifiées à la faveur de la mise en service du TGV-A.TGV-Atlantique ; transport ferroviaire ; transport à grande vitesse ; choix du mode de transport ; déplacement domicile-travail; mobilité professionnelle ; déplacement personnel ; enquête ; étude avant-après

Appl Environ Microbiol

Understanding the mechanisms behind the typicity of regional wines inevitably brings attention to microorganisms associated with their production. Oenococcus oeni is the main bacterial species involved in wine and cider making. It develops after the yeast-driven alcoholic fermentation and performs the malolactic fermentation, which improves the taste and aromatic complexity of most wines. Here, we have evaluated the diversity and specificity of O. oeni strains in six regions. A total of 235 wines and ciders were collected during spontaneous malolactic fermentations and used to isolate 3,212 bacterial colonies. They were typed by multilocus variable analysis, which disclosed a total of 514 O. oeni strains. Their phylogenetic relationships were evaluated by a second typing method based on single nucleotide polymorphism (SNP) analysis. Taken together, the results indicate that each region holds a high diversity of strains that constitute a unique population. However, strains present in each region belong to diverse phylogenetic groups, and the same groups can be detected in different regions, indicating that strains are not genetically adapted to regions. In contrast, greater strain identity was seen for cider, white wine, or red wine of Burgundy, suggesting that genetic adaptation to these products occurred. This study reports the isolation, genotyping, and geographic distribution analysis of the largest collection of O. oeni strains performed to date. It reveals that there is very high diversity of strains in each region, the majority of them being detected in a single region. The study also reports the development of an SNP genotyping method that is useful for analyzing the distribution of O. oeni phylogroups. The results show that strains are not genetically adapted to regions but to specific types of wines. They reveal new phylogroups of strains, particularly two phylogroups associated with white wines and red wines of Burgundy. Taken together, the results shed light on the diversity and specificity of wild strains of O. oeni, which is crucial for understanding their real contribution to the unique properties of wines.Multi-strain indigenous Yeast and Bacterial starters for ‘Wild-ferment’ Wine productio

SSU1 Checkup, a Rapid Tool for Detecting Chromosomal Rearrangements Related to the SSU1 Promoter in Saccharomyces cerevisiae: An Ecological and Technological Study on Wine Yeast

Chromosomal rearrangements (CR) such as translocations, duplications and inversions play a decisive role in the adaptation of microorganisms to specific environments. In enological Saccharomyces cerevisiae strains, CR involving the promoter region of the gene SSU1 lead to a higher sulfite tolerance by enhancing the SO2 efflux. To date, three different SSU1 associated CR events have been described, including translocations XV-t-XVI and VIII-t-XVI and inversion inv-XVI. In the present study, we developed a multiplex PCR method (SSU1 checkup) that allows a rapid characterization of these three chromosomal configurations in a single experiment. Nearly 600 S. cerevisiae strains collected from fermented grape juice were genotyped by microsatellite markers. We demonstrated that alleles of the SSU1 promoter are differently distributed according to the wine environment (cellar versus vineyard) and the nature of the grape juice. Moreover, rearranged SSU1 promoters are significantly enriched among commercial starters. In addition, the analysis of nearly isogenic strains collected in wine related environments demonstrated that the inheritance of these CR shapes the genetic diversity of clonal populations. Finally, the link between the nature of SSU1 promoter and the tolerance to sulfite was statistically validated in natural grape juice containing various SO2 concentrations. The SSU1 checkup is therefore a convenient new tool for addressing population genetics questions and for selecting yeast strains by using molecular markers.Fil: Marullo, Philippe. Universite de Bordeaux; FranciaFil: Claisse, Olivier. Universite de Bordeaux; FranciaFil: Raymond Eder, María Laura. Universidad Católica de Córdoba. Instituto de Investigaciones en Recursos Naturales y Sustentabilidad José Sanchez Labrador S. J. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Recursos Naturales y Sustentabilidad José Sanchez Labrador S. J.; ArgentinaFil: Börlin, Marine. Universite de Bordeaux; FranciaFil: Feghali, Nadine. Lebanese University; LíbanoFil: Bernard, Margaux. Universite de Bordeaux; FranciaFil: Legras, Jean Luc. Université Montpellier II; FranciaFil: Albertin, Warren. Universite de Bordeaux; FranciaFil: Rosa, Alberto Luis. Universidad Católica de Córdoba. Instituto de Investigaciones en Recursos Naturales y Sustentabilidad José Sanchez Labrador S. J. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Recursos Naturales y Sustentabilidad José Sanchez Labrador S. J.; ArgentinaFil: Masneuf Pomarede, Isabelle. Universite de Bordeaux; Franci

Distribution of prophages in the oenococcus oeni species

Oenococcus oeni is the most exploited lactic acid bacterium in the wine industry and drives the malolactic fermentation of wines. Although prophage-like sequences have been identified in the species, many are not characterized, and a global view of their integration and distribution amongst strains is currently lacking. In this work, we analyzed the complete genomes of 231 strains for the occurrence of prophages, and analyzed their size and positions of insertion. Our data show the limited variation in the number of prophages in O. oeni genomes, and that six sites of insertion within the bacterial genome are being used for site-specific recombination. Prophage diversity patterns varied significantly for different host lineages, and environmental niches. Overall, the findings highlight the pervasive presence of prophages in the O. oeni species, their role as a major source of within-species bacterial diversity and drivers of horizontal gene transfer. Our data also have implications for enhanced understanding of the prophage recombination events which occurred during evolution of O. oeni, as well as the potential of prophages in influencing the fitness of these bacteria in their distinct niches.Evolution expérimentale en mileu extrême de la bactérie lactique Oenococcus oeni et applications à la sélection de levains malo-lactiques plus performant

Front Microbiol

Chromosomal rearrangements (CR) such as translocations, duplications and inversions play a decisive role in the adaptation of microorganisms to specific environments. In enological strains, CR involving the promoter region of the gene lead to a higher sulfite tolerance by enhancing the SO efflux. To date, three different associated CR events have been described, including translocations XV-t-XVI and VIII-t-XVI and inversion inv-XVI. In the present study, we developed a multiplex PCR method ( checkup) that allows a rapid characterization of these three chromosomal configurations in a single experiment. Nearly 600 strains collected from fermented grape juice were genotyped by microsatellite markers. We demonstrated that alleles of the promoter are differently distributed according to the wine environment (cellar versus vineyard) and the nature of the grape juice. Moreover, rearranged promoters are significantly enriched among commercial starters. In addition, the analysis of nearly isogenic strains collected in wine related environments demonstrated that the inheritance of these CR shapes the genetic diversity of clonal populations. Finally, the link between the nature of promoter and the tolerance to sulfite was statistically validated in natural grape juice containing various SO concentrations. The checkup is therefore a convenient new tool for addressing population genetics questions and for selecting yeast strains by using molecular markers

Two different Oenococcus oeni lineages are associated to either red or white wines in Burgundy: genomics and metabolomics insights

Oenococcus oeni is the bacterium most often associated with spontaneous malolactic fermentation (MLF) of wine. During MLF, malic acid is transformed into lactic acid and several metabolites are modified, modulating wine’s total acidity and improving its sensory properties. Previous works have suggested that certain genetic groups of O. oeni strains are associated to different kinds of products. In the present study we have spotted two groups of strains isolated mainly from Burgundy wines, one associated to red wines and the other to white wines. Sequencing 14 genomes of red and white wine strains revealed that they share a common ancestor that probably colonised two different substrates –red and white wine-associated environments–, diverging over time and disseminating to various regions. Their capacity to perform MLF and modify the volatile profile of wine was determined by fermenting a chardonnay wine and analysing its volatile fraction with a non-targeted metabolomics approach by GC-MS. The strains had a different impact on the volatile composition depending on their group of origin. These results show for the first time a correspondence between the product of origin of the strains and the volatile profile of the wines they produce. Furthermore, the genetic features that might be implied in these different phenotypes are examined

Détection de bactéries lactiques produisant du 3-hydroxypropionaldéhyde (précurseur d'acroléine) à partir du glycérol par tests moléculaires

National audienc

Détection de bactéries lactiques produisant du 3-hydroxypropionaldéhyde (précurseur d'acroléine) à partir du glycérol par tests moléculaires

National audienc

Le TGV-Atlantique : entre récession et concurrence: Evolution de la mobilité et mise en service du TGV-Atlantique : analyse des enquêtes réalisées en septembre 1989 et septembre 1993

ISSN 0769-6434Le TGV véhicule bien des images. Train des Parisiens ou de la décentralisation ? Vitesse démocratisée ou tarifs élevés ? Train d'affaires ou service public ? Le TGV transporte d'abord des voyageurs. Qui sont-ils ? Que font-ils ? Quelles sont leurs spécificités par rapport aux voyageurs utilisant un autre moyen de transports ? Sont-ils différents de ceux qui voyageaient avant sa mise en service ? En d'autres termes, quelles transformations de la mobilité tant professionnelle que personnelle peuvent-elles être reliées à la mise en service du TGV ?Pour répondre à ces questions, une enquête coordonnée sur les trois modes de transport (autoroute, avion, train) a été réalisée à l'initiative de l'Observatoire Economique et Statistique des Transports par le Laboratoire d'Economie des Transport en 1989 et en 1993 autour du TGV-Atlantique. Cette enquête, intervenue juste avant et quatre ans après la mise en service du TGV-Atlantique, a permis de recueillir 18.000 questionnaires portant sur l'ensemble des parcours Province-Paris concernés par la nouvelle offre. Cette synthèse des résultats permet de mieux comprendre comment les déplacement professionnels, les déplacements domicile-travail, les déplacements personnels ainsi que les relations entre l'Ile-de-France et les principales agglomérations de la façade atlantique de la France se sont modifiées à la faveur de la mise en service du TGV-A

Organisation of the genes encoding glycerol dehydratase of Lactobacillus collinoides, Lactobacillus hilgardii and Lactobacillus diolivorans

International audienceLactobacillus collinoides ICEB 9527, Lactobacillus hilgardii ICEB 0003 and strain ICEB 0004 belonging to the recently described Lactobacillus diolivorans species which could degrade glycerol in anaerobic conditions were studied. Two degenerated primers, deduced from Citrobacter freundii, Klebsiella pneumoniae, Klebsiella oxytoca, Salmonella typhimurium and Clostridium pasteurianum glycerol dehydratase sequence alignments, were used for polymerase chain reaction amplification. The three 279 base pair amplicons from L. collinoides, L. hilgardii and L. diolivorans showed high homologies with part of the glycerol dehydratase genes already sequenced. The three amplicon DNA nucleotide sequences were used to design specific primers for inverse-PCR in order to study the entire glycerol dehydratase genes of the three species. Amplified fragments were cloned and then sequenced, several open reading frames were identified. For the three species, the genetic organization of the glycerol degradation genes suggested operons. Some deduced proteins were very similar to the carbon dioxide concentrating protein family. The others are three subunits similar to adenosylcobalamin dependent glycerol or propanediol dehydratases respectively from C. freundii, K. pneumoniae and K. oxytoca and S. typhimurium