# Bifidobacteria exhibit social behavior through carbohydrate resource sharing in the gut

## TL;DR

Bifidobacteria in the gut can break down carbohydrates and share these resources with other microbes, shaping the gut microbiome.

## Contribution

This study reveals that bifidobacteria have extensive carbohydrate-degrading genes and may engage in resource sharing through metabolic specialization.

## Key findings

- Bifidobacteria have more carbohydrate-related genes than many other gut microbes.
- Transcriptome data supports bifidobacterial involvement in glycan metabolism.
- Bifidobacteria may share carbohydrate resources through cross-feeding and metabolic specialization.

## Abstract

Bifidobacteria are common and frequently dominant members of the gut microbiota of
many animals, including mammals and insects. Carbohydrates are considered key carbon
sources for the gut microbiota, imposing strong selective pressure on the complex
microbial consortium of the gut. Despite its importance, the genetic traits that
facilitate carbohydrate utilization by gut microbiota members are still poorly
characterized. Here, genome analyses of 47 representative Bifidobacterium
(sub)species revealed the genes predicted to be required for the degradation and
internalization of a wide range of carbohydrates, outnumbering those found in many
other gut microbiota members. The glycan-degrading abilities of bifidobacteria are
believed to reflect available carbon sources in the mammalian gut. Furthermore,
transcriptome profiling of bifidobacterial genomes supported the involvement of
various chromosomal loci in glycan metabolism. The widespread occurrence of
bifidobacterial saccharolytic features is in line with metagenomic and
metatranscriptomic datasets obtained from human adult/infant faecal samples, thereby
supporting the notion that bifidobacteria expand the human glycobiome. This study
also underscores the hypothesis of saccharidic resource sharing among bifidobacteria
through species-specific metabolic specialization and cross feeding, thereby forging
trophic relationships between members of the gut microbiota.