Phylogenomic analysis of lactobacillus curvatus reveals two lineages distinguished by genes for fermenting plant-derived carbohydrates

Lactobacillus curvatus is a lactic acid bacterium encountered in many different types of fermented food (meat, seafood, vegetables, and cereals). Although this species plays an important role in the preservation of these foods, few attempts have been made to assess its genomic diversity. This study uses comparative analyses of 13 published genomes (complete or draft) to better understand the evolutionary processes acting on the genome of this species. Phylogenomic analysis, based on a coalescent model of evolution, revealed that the 6,742 sites of single nucleotide polymorphism within the L. curvatus core genome delineate two major groups, with lineage 1 represented by the newly sequenced strain FLEC03, and lineage 2 represented by the type-strain DSM20019. The two lineages could also be distinguished by the content of their accessory genome, which sheds light on a long-term evolutionary process of lineage-dependent genetic acquisition and the possibility of population structure. Interestingly, one clade from lineage 2 shared more accessory genes with strains of lineage 1 than with other strains of lineage 2, indicating recent convergence in carbohydrate catabolism. Both lineages had a wide repertoire of accessory genes involved in the fermentation of plant-derived carbohydrates that are released from polymers of α/β-glucans, α/β-fructans, and N-acetylglucosan. Other gene clusters were distributed among strains according to the type of food from which the strains were isolated. These results give new insight into the ecological niches in which L. curvatus may naturally thrive (such as silage or compost heaps) in addition to fermented food.Fil: Teran, Lucrecia Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Coeuret, Gwendoline. Institut National de la Recherche Agronomique; FranciaFil: Raya, Raul Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Zagorec, Monique. Institut National de la Recherche Agronomique; FranciaFil: Champomier-Vergès, Marie-Christine. Institut National de la Recherche Agronomique; FranciaFil: Chaillou, Stéphane. Institut National de la Recherche Agronomique; Franci

A polyphasic approach to study the dynamics of microbial population of an organic wheat sourdough during its conversion to gluten-free sourdough

To develop a method for organic gluten-free (GF) sourdough bread production, a long-term and original wheat sourdough was refreshed with GF flours. The dynamics of the sourdough microbiota during five months of back-slopping were analyzed by classical enumeration and molecular methods, including PCR-temporal temperature gel electrophoresis (PCR-TTGE), multiplex PCR, and pulsed field gel electrophoresis (PFGE). The results showed that the yeast counts remained constant, although Saccharomyces cerevisiae, present in the initial wheat sourdough, was no longer detected in the GF sourdough, while lactic acid bacteria (LAB) counts increased consistently. In the first phase, which was aimed at obtaining a GF sourdough from wheat sourdough, Lactobacillus sanfranciscensis, L. plantarum, and L. spicheri were the main LAB species detected. During the second phase, aimed at maintaining the GF sourdough, the L. plantarum and L. spicheri populations decreased whereas L. sanfranciscensis persisted and L. sakei became the predominant species. Multiplex PCRs also revealed the presence of several L. sakei strains in the GF sourdough. In a search for the origin of the LAB species, PCR-TTGE was performed on the flour samples but only L. sanfranciscensis was detected, suggesting a flour origin for this typical sourdough species. Thus, while replacement of the wheat flour by GF flour influenced the sourdough microbiota, some of the original sourdough LAB and yeast species remained in the GF sourdough. [Int Microbiol 2014; 17(1):1-9]Keywords: Lactobacillus spp. · Saccharomyces · Candida ·  sourdough · gluten-free food · organic · lactic acid bacteria · yeas

Nucleotide sequence and analysis of pRC12 and pRC18, two theta-replicating plasmids harbored by Lactobacillus curvatus CRL 705

The nucleotide sequences of plasmids pRC12 (12,342 bp; GC 43.99%) and pRC18 (18,664 bp; GC 34.33%), harbored by the bacteriocin-producer Lactobacillus curvatus CRL 705, were determined and analyzed. Plasmids pRC12 and pRC18 share a region with high DNA identity (> 83% identity between RepA, a Type II toxin-antitoxin system and a tyrosine integrase genes) and are stably maintained in their natural host L. curvatus CRL 705. Both plasmids are low copy number and belong to the theta-type replicating group. While pRC12 is a pUCL287-like plasmid that possesses iterons and the repA and repB genes for replication, pRC18 harbors a 168 amino acid replication protein affiliated to RepB, which was named RepB’. Plasmid pRC18 also possesses a pUCL287-like repA gene but it was disrupted by an 11 kb insertion element that contains RepB’, several transposases/IS elements, and the lactocin Lac705 operon. An Escherichia coli / Lactobacillus shuttle vector, named plasmid p3B1, carrying the pRC18 replicon (i.e. repB’ and replication origin), a chloramphenicol resistance gene and a pBluescript backbone, was constructed and used to define the host range of RepB’. Chloramphenicol-resistant transformants were obtained after electroporation of Lactobacillus plantarum CRL 691, Lactobacillus sakei 23K and a plasmid-cured derivative of L. curvatus CRL 705, but not of L. curvatus DSM 20019 or Lactococcus lactis NZ9000. Depending on the host, transformation efficiency ranged from 102 to 107 per μg of DNA; in the new hosts, the plasmid was relatively stable as 29–53% of recombinants kept it after cell growth for 100 generations in the absence of selective pressure. Plasmid p3B1 could therefore be used for cloning and functional studies in several Lactobacillus species.Fil: Teran, Lucrecia Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Cuozzo, Sergio Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Aristimuño Ficoseco, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Fadda, Silvina G.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Chaillou, Stéphane. Institut National de la Recherche Agronomique; FranciaFil: Champomier Vergès, Marie Christine. Institut National de la Recherche Agronomique; FranciaFil: Zagorec, Monique. Institut National de la Recherche Agronomique; FranciaFil: Hebert, Elvira Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Raya, Raul Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

Complete Chromosome Sequence of Carnobacterium maltaromaticum LMA 28

Within the lactic acid bacterium genus Carnobacterium, Carnobacterium maltaromaticum is one of the most frequently isolated species from natural environments and food. It potentially plays a major role in food product biopreservation. We report here on the 3.649-Mb chromosome sequence of C. maltaromaticum LMA 28, which was isolated from ripened soft cheese

Pangenomic analysis of the four species within the Lactobacillus sakei phylogenetic clade

Pangenomic analysis of the four species within the Lactobacillus sakei phylogenetic clade. 5. international symposium on lactic acid bacteri

Transport of d-Xylose in Lactobacillus pentosus, Lactobacillus casei, and Lactobacillus plantarum: Evidence for a Mechanism of Facilitated Diffusion via the Phosphoenolpyruvate:Mannose Phosphotransferase System

We have identified and characterized the d-xylose transport system of Lactobacillus pentosus. Uptake of d-xylose was not driven by the proton motive force generated by malolactic fermentation and required d-xylose metabolism. The kinetics of d-xylose transport were indicative of a low-affinity facilitated-diffusion system with an apparent K(m) of 8.5 mM and a V(max) of 23 nmol min(−1) mg of dry weight(−1). In two mutants of L. pentosus defective in the phosphoenolpyruvate:mannose phosphotransferase system, growth on d-xylose was absent due to the lack of d-xylose transport. However, transport of the pentose was not totally abolished in a third mutant, which could be complemented after expression of the L. curvatus manB gene encoding the cytoplasmic EIIB(Man) component of the EII(Man) complex. The EII(Man) complex is also involved in d-xylose transport in L. casei ATCC 393 and L. plantarum 80. These two species could transport and metabolize d-xylose after transformation with plasmids which expressed the d-xylose-catabolizing genes of L. pentosus, xylAB. L. casei and L. plantarum mutants resistant to 2-deoxy-d-glucose were defective in EII(Man) activity and were unable to transport d-xylose when transformed with plasmids containing the xylAB genes. Finally, transport of d-xylose was found to be the rate-limiting step in the growth of L. pentosus and of L. plantarum and L. casei ATCC 393 containing plasmids coding for the d-xylose-catabolic enzymes, since the doubling time of these bacteria on d-xylose was proportional to the level of EII(Man) activity

Concept de Salle Virtuelle d'Interaction Collaborative

National audienceCet article présente la conception d’un environnement d’interaction collaborative dédié au travail colocalisé de type war room. Pour cela nous mettons en place une architecture logicielle distribuée s’appuyant sur un paradigme MVO (modèle, vue, outil). La distribution logicielle de cette plate-forme permet d’offrir à une équipe d’utilisateurs spécialisés des modalités d’interaction diverses, grâce à l’utilisation de dispositifs matériels hétérogènes