Human gut Bifidobacterium longum subsp. suillum is enriched in vitro by a pectic polysaccharide isolated from the flowers of Lilium lancifolium

Although pectins have been explored widely, knowledge of their effects on the gut microbiota is lacking owing their complex structure. The aim of this study was to investigate whether pectin enriched gut microbes in vitro. To address this, a homogeneous RG-I like pectin, L01-B1, with a molecular weight of 43.9 kDa was extracted from the flowers of Lilium lancifolium. Structural analysis revealed that L01-B1 contained rhamnose, glucuronic acid, galacturonic acid, galactose, and arabinose in a molar ratio of 13.4: 1.8: 11.1: 37.2: 36.5. The backbone of L01-B1 was composed of 1, 6-β-Galp, 1, 4-α-GalpA, and 1, 2-α-Rhap, whereas the branches included 1, 5-α-Araf, 1, 4-β-Galp, and T-β-GlcpA attached to C-4 of rhamnose, and 1, 3-β-Galp and T-β-Galp linked to C-3 of galactose. L01-B1 altered the composition of human gut microbiota in vitro and increased the abundance of Bifidobacterium longum. Furthermore, Bifidobacterium longum subsp. suillum strain DK001 was isolated and identified from human feces. The DK001 genome was found to be circular with a genome size of approximately 2.4 M. Notably, L01-B1 might possibly be degraded by two kinds of enzymes and change the metabolism of human gut microbiota. Overall, these findings provide insights into intervention strategies that target Bifidobacterium longum.