Genome Analysis and Characterisation of the Exopolysaccharide Produced by Bifidobacterium longum subsp. longum 35624™

Abstract

The Bifibobacterium longum subsp. longum 35624™ strain (formerly named Bifidobacterium longum subsp. infantis) is a well described probiotic with clinical efficacy in Irritable Bowel Syndrome clinical trials and induces immunoregulatory effects in mice and in humans. This paper presents (a) the genome sequence of the organism allowing the assignment to its correct subspeciation longum; (b) a comparative genome assessment with other B. longum strains and (c) the molecular structure of the 35624 exopolysaccharide (EPS624). Comparative genome analysis of the 35624 strain with other B. longum strains determined that the sub-speciation of the strain is longum and revealed the presence of a 35624-specific gene cluster, predicted to encode the biosynthetic machinery for EPS624. Following isolation and acid treatment of the EPS, its chemical structure was determined using gas and liquid chromatography for sugar constituent and linkage analysis, electrospray and matrix assisted laser desorption ionization mass spectrometry for sequencing and NMR. The EPS consists of a branched hexasaccharide repeating unit containing two galactose and two glucose moieties, galacturonic acid and the unusual sugar 6-deoxy-L-talose. These data demonstrate that the B. longum 35624 strain has specific genetic features, one of which leads to the generation of a characteristic exopolysaccharide.

The First Microbial Colonizers of the Human Gut: Composition, Activities, and Health Implications of the Infant Gut Microbiota

“…Notably, such novel findings imply that capsular structures of bifidobacteria play an important role in their host against pathological cell shedding (407). Furthermore, it has been shown that EPS produced by B. longum 35624 exerts an immune modulatory role by dampening proinflammatory host responses, while loss of EPS production results in the induction of local TH17 responses (408,409).…”

The Surface-Associated Exopolysaccharide of Bifidobacterium longum 35624 Plays an Essential Role in Dampening Host Proinflammatory Responses and Repressing Local T H 17 Responses

“…We recently described that the B. longum 35624 strain-specific EPS gene cluster, designated the EPS 624 cluster, is responsible for the production of a cell surface-associated exopolysaccharide (sEPS) composed of a branched hexasaccharide repeating unit with two galactoses, two glucoses, galacturonic acid, and the unusual sugar 6-deoxytalose (23). The overall aim of the current study was to determine whether the exopolysaccharide produced by B. longum 35624 is related to the immunoregulatory effects of this microorganism.…”

“…The exopolysaccharide was isolated as previously described (23). Briefly, following harvesting of B. longum 35624 cells, which were grown on agar plates to minimize carryover of medium components, an exopolysaccharide solution was generated by agitating the cells in phosphate-buffered saline (PBS).…”

Bifidobacterium infantis 35624 and other probiotics in the management of irritable bowel syndrome. Strain specificity, symptoms, and mechanisms

“…Furthermore, very recent genomic analyses have reclassified B. infantis 35624 as B. longum subsp. longum 35624 11,12 . This further underscores the importance of using strain designations (35624) rather than genus/species to identify individual strains, and highlights that the Yuan et al meta-analysis does not, therefore, even include probiotic organisms belonging to the same sub-species.…”