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We have shown that bacterial mutation rates change during the experimental colonization of the mouse gut. A high mutation rate was initially beneficial because it allowed faster adaptation, but this benefit disappeared once adaptation was achieved. Mutator bacteria accumulated mutations that, although neutral in the mouse gut, are often deleterious in(More)
Lactobacillus fermentum is a lactic acid bacterial species commonly found in the digestive tracts of pigs and rodents and also present in man. We characterized a 5.7-kb plasmid, pLEM3, conferring erythromycin resistance, which was isolated from a porcine strain of L. fermentum. Plasmid pLEM3 established efficiently in L. fermentum, conferred high-level(More)
Ruminococcin A (RumA) is a trypsin-dependent lantibiotic produced by Ruminococcus gnavus E1, a gram-positive strict anaerobic strain isolated from a human intestinal microbiota. A 12.8-kb region from R. gnavus E1 chromosome, containing the biosynthetic gene cluster of RumA, has been cloned and sequenced. It consisted of 13 open reading frames, organized in(More)
When cultivated in the presence of trypsin, the Ruminococcus gnavus E1 strain, isolated from a human fecal sample, was able to produce an antibacterial substance that accumulated in the supernatant. This substance, called ruminococcin A, was purified to homogeneity by reverse-phase chromatography. It was shown to be a 2,675-Da bacteriocin harboring a(More)
Commensal bacteria often have an especially rich source of glycan-degrading enzymes which allow them to utilize undigested carbohydrates from the food or the host. The species Ruminococcus gnavus is present in the digestive tract of ≥90% of humans and has been implicated in gut-related diseases such as inflammatory bowel diseases (IBD). Here we analysed the(More)
Fourteen bacterial strains capable of producing a trypsin-dependent antimicrobial substance active against Clostridium perfringens were isolated from human fecal samples of various origins (from healthy adults and children, as well as from adults with chronic pouchitis). Identification of these strains showed that they belonged to Ruminococcus gnavus,(More)
A strain of Lactobacillus paracasei subsp. paracasei BMK2005 isolated from healthy infant faeces has shown a remarkable antibacterial activity against 32 bacterial pathogenic strains of human clinical isolates. Among them, 13 strains belonging to species of Escherichia coli, Citrobacter freundii, Citrobacter diversus, Klebsiella oxytoca, Enterobacter(More)
The M6 protein from Streptococcus pyogenes is the best-characterized member of a family of cell envelope-associated proteins. Based on the observation that the C-terminal sorting signals of these proteins can drive cell wall anchoring of heterologous unanchored proteins, we have cloned and expressed the emm6 structural gene for the M6 protein in various(More)
The use of genetically modified organisms (GMO) in dairy products requires evaluation of the DNA transfer capacity from such organisms among the human intestinal microflora. Thus, both in vitro and in vivo [in the digestive tract (DT) of mice] transfer from Lactococcus lactis donor strains of the conjugative plasmid pIL205 (CmR) and the non-conjugative(More)