Vincent Sanchis

Publications (34) View all

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  Available from: Vincent Sanchis

  Article: Pathogenic potential of B. cereus strains revealed by phenotypic analysis.

  Rita Kamar, Michel Gohar, Isabelle Jéhanno, Agnès Réjasse, Mireille Kallassy, Didier Lereclus, Vincent Sanchis, Nalini Ramarao
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  ABSTRACT: B. cereus pathogenic spectrum ranges from strains used as probiotics, to human lethal strains. However, prediction of the pathogenic potential of a strain remains difficult. Here, we show that food poisoning and clinical strains can be differentiated from harmless strains on the basis of host colonization phenotypes.
  Journal of clinical microbiology 11/2012; · 4.16 Impact Factor
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  Article: Identification of Bacillus cereus genes specifically expressed during growth at low temperatures.

  Julien Brillard, Isabelle Jéhanno, Claire Dargaignaratz, Isabelle Barbosa, Christian Ginies, Frédéric Carlin, Sinda Fedhila, Christophe Nguyen-the, Véronique Broussolle, Vincent Sanchis
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  ABSTRACT: The mechanisms involved in the ability of Bacillus cereus to multiply at low temperatures were investigated. It was assumed that many genes involved in cold acclimation would be upregulated at low temperatures. Recombinase-based in vivo expression technology (IVET) was adapted to the detection of the transient activation of B. cereus promoters during growth at 10 degrees C. Four independent screenings of a promoter library from type strain ATCC 14579 were performed, and 17 clones were isolated. They corresponded to 17 promoter regions that displayed reproducibly elevated expression at 10 degrees C relative to expression at 30 degrees C. This analysis revealed several genes that may be important for B. cereus to grow successfully under the restrictive conditions of cold habitats. Among them, a locus corresponding to open reading frames BC5402 to BC5398, harboring a lipase-encoding gene and a putative transcriptional regulator, was identified three times. While a mutation in the putative regulator-encoding gene did not cause any particular phenotype, a mutant deficient in the lipase-encoding gene showed reduced growth abilities at low temperatures compared with the parental strain. The mutant did not change its fatty acid profiles in the same way as the wild type when grown at 12 degrees C instead of 37 degrees C. This study demonstrates the feasibility of a promoter trap strategy for identifying cold-induced genes. It outlines a first picture of the different processes involved in B. cereus cold acclimation.
  Applied and environmental microbiology 02/2010; 76(8):2562-73. · 3.69 Impact Factor
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  Article: Generation of Mini-Tn10 transposon insertion mutant library of Bacillus thuringiensis for the investigation of genes required for its bacteriocin production.

  Fakher Kamoun, Ines Ben Fguira, Afef Tounsi, Lobna Abdelkefi-Mesrati, Vincent Sanchis, Didier Lereclus, Samir Jaoua
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  ABSTRACT: Bacillus thuringiensis strain BUPM4 is known for its ability to produce a bacteriocin, called Bacthuricin F4 (BF4), which inhibits the growth of several Gram-positive bacteria and particularly Bacillaceae. This study aimed to use the insertional transposon mutagenesis approach for disrupting and thus identifying genes associated with BF4 synthesis. Here, the mini-Tn10 transposon was used to generate a library of B. thuringiensis mutants. Twenty thousand clones were screened for the search of mutants with affected bacteriocin synthesis. By molecular hybridization, it was demonstrated that the mini-Tn10 transposition occurred in different sites. Clone MB1, containing a mini-Tn10 single-copy insertion, lost the BF4 synthesis, but maintained its immunity to BF4. The flanking sequences surrounding the mini-Tn10 insertion were cloned and sequenced. Homology searches of the surrounding ORFs revealed a strong similarity to a phage tail component, which allowed us to postulate that BUPM4 bacteriocin could be a phage tail-like one.
  FEMS Microbiology Letters 06/2009; 294(2):141-9. · 2.04 Impact Factor
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  Article: Ecological diversification in the Bacillus cereus Group.

  Marie-Hélène Guinebretière, Fabiano L Thompson, Alexei Sorokin, Philippe Normand, Peter Dawyndt, Monika Ehling-Schulz, Birgitta Svensson, Vincent Sanchis, Christophe Nguyen-The, Marc Heyndrickx, Paul De Vos
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  ABSTRACT: The Bacillus cereus Group comprises organisms that are widely distributed in the environment and are of health and economic interest. We demonstrate an 'ecotypic' structure of populations in the B. cereus Group using (i) molecular data from Fluorescent Amplified Fragment Length Polymorphism patterns, ribosomal gene sequences, partial panC gene sequences, 'psychrotolerant' DNA sequence signatures and (ii) phenotypic and descriptive data from range of growth temperature, psychrotolerance and thermal niches. Seven major phylogenetic groups (I to VII) were thus identified, with ecological differences that provide evidence for a multiemergence of psychrotolerance in the B. cereus Group. A moderate thermotolerant group (VII) was basal to the mesophilic group I, from which in turn distinct thermal lineages have emerged, comprising two mesophilic groups (III, IV), an intermediate group (V) and two psychrotolerant groups (VI, II). This stepwise evolutionary transition toward psychrotolerance was particularly well illustrated by the relative abundance of the 'psychrotolerant' rrs signature (as defined by Pruss et al.) copies accumulated in strains that varied according to the phylogenetic group. The 'psychrotolerant' cspA signature (as defined by Francis et al.) was specific to group VI and provided a useful way to differentiate it from the psychrotolerant group II. This study illustrates how adaptation to novel environments by the modification of temperature tolerance limits has shaped historical patterns of global ecological diversification in the B. cereus Group. The implications for the taxonomy of this Group and for the human health risk are discussed.
  Environmental Microbiology 05/2008; 10(4):851-65. · 5.84 Impact Factor
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  Article: Extending the Bacillus cereus group genomics to putative food-borne pathogens of different toxicity.

  Alla Lapidus, Eugene Goltsman, Sandrine Auger, Nathalie Galleron, Béatrice Ségurens, Carole Dossat, Miriam L Land, Veronique Broussolle, Julien Brillard, Marie-Helene Guinebretiere, Vincent Sanchis, Christophe Nguen-The, Didier Lereclus, Paul Richardson, Patrick Wincker, Jean Weissenbach, S Dusko Ehrlich, Alexei Sorokin
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  ABSTRACT: The Bacillus cereus group represents sporulating soil bacteria containing pathogenic strains which may cause diarrheic or emetic food poisoning outbreaks. Multiple locus sequence typing revealed a presence in natural samples of these bacteria of about 30 clonal complexes. Application of genomic methods to this group was however biased due to the major interest for representatives closely related to Bacillus anthracis. Albeit the most important food-borne pathogens were not yet defined, existing data indicate that they are scattered all over the phylogenetic tree. The preliminary analysis of the sequences of three genomes discussed in this paper narrows down the gaps in our knowledge of the B. cereus group. The strain NVH391-98 is a rare but particularly severe food-borne pathogen. Sequencing revealed that the strain should be a representative of a novel bacterial species, for which the name Bacillus cytotoxis or Bacillus cytotoxicus is proposed. This strain has a reduced genome size compared to other B. cereus group strains. Genome analysis revealed absence of sigma B factor and the presence of genes encoding diarrheic Nhe toxin, not detected earlier. The strain B. cereus F837/76 represents a clonal complex close to that of B. anthracis. Including F837/76, three such B. cereus strains had been sequenced. Alignment of genomes suggests that B. anthracis is their common ancestor. Since such strains often emerge from clinical cases, they merit a special attention. The third strain, KBAB4, is a typical facultative psychrophile generally found in soil. Phylogenic studies show that in nature it is the most active group in terms of gene exchange. Genomic sequence revealed high presence of extra-chromosomal genetic material (about 530kb) that may account for this phenomenon. Genes coding Nhe-like toxin were found on a big plasmid in this strain. This may indicate a potential mechanism of toxicity spread from the psychrophile strain community. The results of this genomic work and ecological compartments of different strains incite to consider a necessity of creating prophylactic vaccines against bacteria closely related to NVH391-98 and F837/76. Presumably developing of such vaccines can be based on the properties of non-pathogenic strains such as KBAB4 or ATCC14579 reported here or earlier. By comparing the protein coding genes of strains being sequenced in this project to others we estimate the shared proteome, or core genome, in the B. cereus group to be 3000+/-200 genes and the total proteome, or pan-genome, to be 20-25,000 genes.
  Chemico-Biological Interactions 02/2008; 171(2):236-49. · 2.46 Impact Factor