Structural investigation of polysaccharides extracted from four Bifidobacterium breve strains

Bifidobacterium breve is a common component of the human gut microbiota, particularly in infancy. Its surface-exposed polysaccharides may be important for its purported health-promoting activities and may serve various functions such as immune evasion and modulation, environmental stress protection, or carbohydrate substrate provision for other gut commensals. In the present work, we extracted and analysed polysaccharides from four strains of B. breve. Their chemical structure was established by 2D NMR spectroscopy and methylation analysis. Most analysed strains produced several distinct saccharidic structures, some of which contained common rhamnan substructures. The uncovered complexity and multitude of polysaccharides produced by representatives of a single species of the Bifidobacterium genus illustrates clear strain specificity which may underpin probiotic and other properties of this group of human gut commensals.