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Marie-Lise Dillmann

Publications and source records attributed to Marie-Lise Dillmann.

4 recordsLinked to original sources
PubMed2005

Influence of fermentation medium composition on physicochemical surface properties of Lactobacillus acidophilus.

The effect of the simple and complex basic components of a fermentation medium on the surface properties of Lactobacillus acidophilus NCC2628 is studied by physicochemical methods, such as electrophoresis, interfacial adhesion, and X-ray photonelectron spectroscopy, and by transmission electron microscopy. Starting from an optimized complete medium, the effect of carbohydrates, peptones, and yeast extracts on the physicochemical properties of the cell wall is systematically investigated by consecutively omitting one of the principal components from the fermentation medium at the time. The physicochemical properties and structure of the bacterial cell wall remain largely unchanged if the carbohydrate content of the fermentation medium is strongly reduced, although the concentration of surface proteins increases slightly. Both peptone and yeast extract have a considerable influence on the bacterial cell wall, as witnessed by changes in surface charge, hydrophobicity, and the nitrogen-to-carbon ratio. Both zeta potential and the cell wall hydrophobicity show a positive correlation with the nitrogen-to-carbon ratio of the bacterial surfaces, indicative of the important role of surface proteins in the overall surface physical chemistry. The hydrophobicity of the cell wall, which is low for the cultures grown in the complete medium and in the absence of carbohydrates, becomes fairly high for the cultures grown in the medium without peptones and the medium without yeast extract. UV spectrophotometry and sodium dodecyl sulfate-polyacrylamide gel electrophoresis combined with liquid chromatography-tandem mass spectrometry are used to analyze the effect of medium composition on LiCl-extractable cell wall proteins, confirming the major change in protein composition of the cell wall for the culture fermented in the medium without peptones. In particular, it is found that expression of the S-layer protein is dependent on the protein source of the fermentation medium.

Bacterial Adhesion↗
PubMed2004

Lactobacillus plantarum bacteriophage LP65: a new member of the SPO1-like genus of the family Myoviridae.

The virulent Lactobacillus plantarum myophage LP65 was isolated from industrial meat fermentation. Tail contraction led to reorganization of the tail sheath and the baseplate; a tail tube was extruded. In ultrathin section the phage adsorbed via its baseplate to the exterior of the cell, while the tail tube tunneled through the thick bacterial cell wall. Convoluted membrane structures were induced in the infected cell. Progeny phage was detected 100 min postinfection, and lysis occurred after extensive digestion of the cell wall. Sequence analysis revealed a genome of 131,573 bp of nonredundant DNA. Four major genome regions and a large tRNA gene cluster were observed. One module corresponded to DNA replication genes. Helicase/primase and two replication/recombination enzymes represented the only links to T4-like Myoviridae from gram-negative bacteria. Another module corresponded to the structural genes. Sequence relatedness identified links with Listeria phage A511, Staphylococcus phage K, and Bacillus phage SPO1. LP65 structural proteins were identified by two-dimensional proteome analysis and mass spectrometry. The putative tail sheath protein showed a shear-induced change in electrophoretic migration behavior. The genome organization of the structural module in LP65 resembled that of Siphoviridae from the lambda supergroup.

Genome, Viral↗
PubMed2004

Isolation of Escherichia coli bacteriophages from the stool of pediatric diarrhea patients in Bangladesh.

A 3-week coliphage survey was conducted in stool samples from 140 Bangladeshi children hospitalized with severe diarrhea. On the Escherichia coli indicator strain K803, all but one phage isolate had 170-kb genomes and the morphology of T4 phage. In spot tests, the individual T4-like phages infected up to 27 out of 40 diarrhea-associated E. coli, representing 22 O serotypes and various virulence factors; only five of them were not infected by any of these new phages. A combination of diagnostic PCR based on g32 (DNA binding) and g23 (major capsid protein) and Southern hybridization revealed that half were T-even phages sensu strictu, while the other half were pseudo-T-even or even more distantly related T4-like phages that failed to cross-hybridize with T4 or between each other. Nineteen percent of the acute stool samples yielded T4-like phages, and the prevalence was lower in convalescent stool samples. T4-like phages were also isolated from environmental and sewage water, but with low frequency and low titers. On the enteropathogenic E. coli strain O127:K63, 14% of the patients yielded phage, all of which were members of the phage family Siphoviridae with 50-kb genomes, showing the morphology of Jersey- and beta-4 like phages and narrow lytic patterns on E. coli O serotypes. Three siphovirus types could be differentiated by lack of cross-hybridization. Only a few stool samples were positive on both indicator strains. Phages with closely related restriction patterns and, in the case of T4-like phages, identical g23 gene sequences were isolated from different patients, suggesting epidemiological links between the patients.

Bacteriophage T4↗