Michel-Yves Mistou

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Lactococcus lactis is a Gram-positive bacteria, which belongs to the group of lactic acid bacteria among which several genera play an essential role in the manufacture of food products. Cytosolic proteins of L. lactis IL1403 cultivated in M17 broth have been resolved by two-dimensional gel electrophoresis using two pH gradients (pH 4-7, 4.5-5.5). More than(More)
Streptococcus agalactiae (group B streptococcus; GBS) is a normal constituent of the intestinal microflora and the major cause of human neonatal meningitis. A single clone, GBS ST-17, is strongly associated with a deadly form of the infection called late-onset disease (LOD), which is characterized by meningitis in infants after the first week of life. The(More)
Lactococcus lactis subsp. cremoris NCDO763 accumulates glycine-betaine (betaine) when submitted to an osmotic stress with NaCl. Betaine transport activity increases with the extent of the osmotic upshock but also with growth temperature, and supplementation of the medium by Tween-80. Fatty acid analysis of the lipid fraction of L. lactis NCDO763 reveals(More)
We have compared the proteomic profiles of L. lactis subsp. cremoris NCDO763 growing in the synthetic medium M17Lac, skim milk microfiltrate (SMM), and skim milk. SMM was used as a simple model medium to reproduce the initial phase of growth of L. lactis in milk. To widen the analysis of the cytoplasmic proteome, we used two different gel systems (pH ranges(More)
The cytoplasmic accumulation of exogenous betaine stimulates the growth of Lactococcus lactis cultivated under hyperosmotic conditions. We report that L. lactis possesses a single betaine transport system that belongs to the ATP-binding cassette (ABC) superfamily of transporters. Through transposon mutagenesis, a mutant deficient in betaine transport was(More)
In Gram-positive bacteria, the functional role of surface polysaccharides (PS) that are not of capsular nature remains poorly understood. Here, we report the presence of a novel cell wall PS pellicle on the surface of Lactococcus lactis. Spontaneous PS-negative mutants were selected using semi-liquid growth conditions, and all mutations were mapped in a(More)
Serine-rich (Srr) proteins exposed at the surface of Gram-positive bacteria are a family of adhesins that contribute to the virulence of pathogenic staphylococci and streptococci. Lectin-binding experiments have previously shown that Srr proteins are heavily glycosylated. We report here the first mass-spectrometry analysis of the glycosylation of(More)
Lactococcus lactis strains from the subsp. cremoris are described as more sensitive to osmotic stress than subsp. lactis strains. We examined the relation between osmotic tolerance and the activity of the betaine transporter BusA among 34 strains of L. lactis. The cremoris strains that showed reduced growth at high osmolality failed to accumulate betaine.(More)
Lactic acid bacteria (LAB) are widely used in the agro-food industry. Some of the LAB also participate in the natural flora in humans and animals. We review here proteomic studies concerning LAB. Two methods of research can be distinguished. In the first one, a systematic mapping of proteins is attempted, which will be useful for taxonomy and to function(More)
Since, like other osmolytes, proline can act as a protein stabilizer, we investigated the thermoprotectant properties of proline in vitro and in vivo. In vivo, elevated proline pools in Escherichia coli (obtained by altering the feedback inhibition by proline of gamma-glutamylkinase, the first enzyme of the proline biosynthesis pathway) restore the(More)