Phylogenetic, Functional and Safety Features of 1950s B. infantis Strains

Abstract

Strains of Bifidobacterium longum subsp. infantis (B. infantis) are amongst the first to colonize the infant gut, partly due to their capacity to metabolize complex human milk oligosaccharides (HMO), and are proposed to play a key role in the development of the infant gut. Since early life, B. infantis supplementation is of high interest, and detailed phylogenetic, functional and safety characterization of the selected strains should be pursued. Using a combination of long and short-read sequencing technologies, we first decipher the genetic distance between different isolates of the same B. infantis strain. Using the same approach, we show that several publicly available genomes recapitulate this strain-level distance as compared to two of the first strains obtained in the 1950s. Furthermore, we demonstrate that the two 1950s B. infantis strains display different functional and safety attributes, as ATCC 15697 is resistant to streptomycin and shows a preference towards lacto-N-tetraose LNT and sialylated HMOs, while LMG 11588 is sensitive to all tested antibiotics and shows a preference towards fucosylated HMOs. Overall, our work highlights that the current diversity observed in B. infantis is likely underestimated and that strain selection within this subspecies must be the subject of scientific pursuit and associated evaluation.

Safety, efficacy, and impact on gut microbial ecology of a Bifidobacterium longum subspecies infantis LMG11588 supplementation in healthy term infants: a randomized, double-blind, controlled trial in the Philippines

“…The B. infantis LMG11588 strain was selected for this clinical trial based on its lack of antibiotic resistance and its capacity to use the abundant fucosylated human milk oligosaccharides (21). The Hi-EG supplement contained 1.8*10 10 CFU B. infantis while the Lo-EG supplement contained 1.0*10 8 CFU B. infantis, both with maltodextrin as excipient.…”

Longitudinal quantification of Bifidobacterium longum subsp. infantis reveals late colonization in the infant gut independent of maternal milk HMO composition

“…infantis ( BL. infantis ) which grows efficiently on most types of HMOs 18 , and possesses a large variability of HMO utilizing genes 19 . In contrast, other Bifidobacterium species have a lower capability of HMO utilization, for example B. breve strains cannot utilize 3′SL and 6′SL at all, and most of them cannot utilize fucosylated HMOs 15 .…”

The Pleiotropic Effects of Carbohydrate-Mediated Growth Rate Modifications in Bifidobacterium longum NCC 2705

“…Strains belonging to B. longum subsp. infantis have been shown to be particularly adapted to import and hydrolyze a range of fucosylated or sialylated HMOs [ 9 , 10 , 11 ], and the capacity to metabolize the neutral Lacto-N-Tetraose (LNT) is considered to be broadly conserved in all subspecies of B. longum [ 7 , 12 ]. In members of the Bifidobacterium genus, carbohydrates are processed through a relatively unique central carbon metabolic pathway, the so-called “bifid-shunt”, which involves the bifunctional xylulose 5-phosphate/fructose-6-phosphate phosphoketolase enzyme (F6PPK) [ 13 ].…”