title: Structural studies of the rhamnose-rich cell wall polysaccharide of Lactobacillus casei BL23.
abstract: Lactobacillus casei is a Gram positive lactic acid bacterium used in dairy fermentations and present in the normal human gut microbiota. Certain strains are recognized as probiotics with beneficial effects on human and animal health. L. casei BL23 is a potential probiotic strain endowed with anti-inflammatory properties and a model strain widely used in genetic, physiological and biochemical studies. A number of bacterial cell surface polysaccharides have been shown to play a role in the immune modulation activities observed for probiotic lactic acid bacteria. In the present work, we purified the most abundant carbohydrate polymer of L. casei BL23 cell wall, a neutral wall polysaccharide (WPS) and established its chemical structure by periodate oxidation, methylation analysis and 2D NMR spectroscopy. The WPS of L. casei BL23 was shown to contain α-Rha, α-Glc, β-GlcNAc and β-GalNAc forming a branched heptasaccharide repeating unit (variant 1) with an additional partial substitution with α-Glc (variant 2). A modified non-reducing end octasaccharide, corresponding to a terminal unit of the WPS (variant 3), was also identified and allowed to define the biological repeating unit of the WPS. To our knowledge, this is the first report of the identification of a biological repeating unit based on a chemical evidence, in a cell wall polysaccharide of a Gram positive bacterial species.
authors.affiliation: National Research Council, 100 Sussex Dr, K1A 0R6 Ottawa, Canada. Electronic address: e.vinogradov59@gmail.com.
authors.forename: Evgeny
authors.initials: E
authors.lastname: Vinogradov
authors.affiliation: Equipe BPA, Université du Littoral-Côte d'Opale, Institut Charles Violette EA 7394, USC Anses, Bd Bassin Napoléon, BP 120, 62327 Boulogne-sur-mer, France. Electronic address: Irina.Sadovskaya@univ-littoral.fr.
authors.forename: Irina
authors.initials: I
authors.lastname: Sadovskaya
authors.affiliation: Equipe BPA, Université du Littoral-Côte d'Opale, Institut Charles Violette EA 7394, USC Anses, Bd Bassin Napoléon, BP 120, 62327 Boulogne-sur-mer, France. Electronic address: thierry.grard@univ-littoral.fr.
authors.forename: Thierry
authors.initials: T
authors.lastname: Grard
authors.affiliation: Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France. Electronic address: marie-pierre.chapot-chartier@inra.fr.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Chapot-Chartier
mesh_terms: D002240:Carbohydrate Sequence; D002473:Cell Wall / Q000737:chemistry*; D000069196:Gastrointestinal Microbiome; D006801:Humans; D007780:Lacticaseibacillus casei / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D011135:Polysaccharides, Bacterial / Q000737:chemistry* / Q000302:isolation & purification; D012210:Rhamnose / Q000032:analysis
chemical_list: D011135:Polysaccharides, Bacterial; D012210:Rhamnose
keywords: Cell wall; Lactobacillus casei; NMR spectroscopy; Polysaccharide; Rhamnose; Structure