Table 1.
Major glycan utilization strategies of bifidobacteria
| Bifidobacterial strains | Types of glycan | Strategies for glycan processing | Metabolites | References |
|---|---|---|---|---|
| B. infantis | ||||
| ATCC 15697 | LNT and LNnT | Hexosaminidase hydrolyzes β 1-3 bonds in LNT and LNnT to release GlcNAc, which is then deacetylated by GlcNAc-6-P deacetylase (nagA) and deaminated by glucosamine-6-P isomerase (nagB). | GlcNAc, acetate, ethanol, formate, and lactate | 149 |
| Bi-26 | 2ʼ-FL | 2ʼ-FL is transported by a special ABC transporter, and the genes encoding fucose peroxidase and ATP transporter are up-regulated during fermentation. | Fucose, acetate, lactate, 1,2-PD, and formate | 150,151 |
| EVC001 | Human milk glycoproteins | Endo-β-N-acetylglucosaminidase releases N-glycans. | Lactate and acetate | 152 |
| B. longum | ||||
| 105-A | Lactulose (contains Gal-β1, 4-Rha structure) | The SBP encoded by the BL105A 0502 gene internalizes lactulose. Gh42β-galactosidase is a candidate enzyme for Gal-β1, 4-RHA degradation. | Acetate and lactate | 153,154 |
| M12 | 2ʼ-FL and LNT | B. longum M12 contains the GH95 gene (α-1-2-L-fucosidase), which can grow on 2ʼ-FL and LNT as the sole carbon source, but lacks GH29 (α-1,3/4-fucosidase) and cannot utilize LNnT. | -- | 46 |
| JCM7052 | Gum arabic AGP | α-l-Rhap-(1 → 4)-β-d-GlcpA-(1 → 6)-β-d-Galp-(1 → 6)-d-Gal tetrasaccharide is produced by the cooperation of three extracellular enzymes including BlArafE, which is a new α-1-arabinofuranosidase (GH43/34) for splitting up the α1,4-Araf linkage. | Oligosaccharides (tet-rasaccharide S4) | 122 |
| JCM7052 | AGP | 3-O-α-D-galactosyl-α-L-arabinofuranosidase (GAfase) (GH39) has responsibility for the release of α-D-Galp-(1 → 3)-L-Ara and β-L-Arap-(1 → 3)-L-Ara. | L-arabinose, and galactose | 54 |
| JCM1217 | Type II AG, and larch wood AG | β-1,6-galactobiose is produced by the combination of three enzymes including GH43_24 exo-β-1,3-galactanase (Bl1,3 Gal), GH30_5 exo-β-1,6-galactobiohydrolase (Bl1,6 Gal) and GH43_22 α-L-arabinofuranosidase (BlArafA). | β-1,6-galactobiose, and arabinofuranose | 16 |
| NCC2705 | High-mannose N-glycan | After cleaving by an endo-β-N-acetylglucosaminidase (GH85), N-glycan is broken down by three GH38 α-mannosidases and a GH125 α-1,6-mannosidase. | Mannose, acetate formate, and ethanol | 56 |
| NCIMB 8809 | Hydroxycinnamic acids (HCAs) | The CaeA esterase in an arabinoxylan/arabinan metabolism cluster can cleave several HCA-containing oligosaccharides. | --- | 155 |
| B. breve | ||||
| UCC2003 | Lacto-N-biose (LNB) | Three transcriptional regulators (LntR, NahR, and NagR1) are involved in regulating LN (n) T/LNB metabolism. | --- | 156 |
| UCC2003 | 4-galactosyl-kojibiose and lactulosucrose | β-galactosidase and the specific gene clusters (Bbr_1551 to Bbr_1553) are used to degrade GOS and lactulose. | -- | 157 |
| DSM 20091 | GOS | GosDEC, GalCDE transporters, and extracellular GH53 enzymes are used to degrade GOS. | -- | 158 |
| JCM1254, JCM7004, TMC3108, and TMC3115 | 2ʼ-FL, 3ʼ-FL, LNnT, and LNFP I | A combination of seven extracellular GH enzymes degrades HMOs, releasing degradants into the extracellular space. | LNB, lactose, galactose, and fucose | 66 |
| B. bifidum | ||||
| JCM1254 | LNT | LNBase (LnbB) is specific for LNT degradation. | lacto-N-biose I and lactose | 45 |
| JCM 1254 | Mucin O-glycans | Degradation of mucin O-glycans by GH 20 sulfoglycosidase (BbhII) and GlcNAc-6S-specific carbohydrate-binding module (CBM) 32. | N-acetylglucosamine-6-sulfate | 71 |
| B. adolescentis | ||||
| P2P3 | High amylose corn starch | RSD1/2/3 and starch-binding modules (CBM25, CBM26 and CBM74) are used for RS degradation. | Maltooligosaccharides | 72 |
| DSMZ 20083 | β-manno-oligosaccharide (MOS) | ABC and MFS transporters facilitate the uptake of linear MOS, while GH1 β-glucosidase and GH32 β-furanoglycosidase catalyze the cleavage of MOS. | Acetate, lactate, and formate | 77 |
| ATCC 15703 | AXOS (DP 2–4 and mono-substituted) | GH43 α-L-arabinofuranosidase is responsible for degradation. | Lactate and acetate | 159 |
| B. pseudocatenulatum | ||||
| MP80 | 2ʼ-FL | A series of gene clusters containing GH29 and GH95 enzymes perform degradation of fucosylated HMOs. | 1, 2-PD | 160 |
| JCM 1200 | Sucrose (Suc) and N-acetyl sucrosamine (SucNAc) | Sucrose phosphorylase is responsible for Suc degradation, and β-fructofuranosidase is for SucNAc. | -- | 85 |
| ED02 | XOS and linear xylan | An extracellular GH10 endo-β-1.4 xylanase exhibits activity against both XOS and xylan. | XOS fractions of the various DP | 161 |
| YIT 4072 T | Arabinoxylan hydrolysate (AXH) | Five GH43 enzymes and three transporters participate in the degradation of AXOS and XOS. | Arabinose and xylose | 162 |
| B. catenulatum subspecies kashiwanohense | ||||
| JCM 15439T | AX, xylan, and XOS | Extracellular xylanase can cleave AX into XOS and AXOS, which are subsequently further catabolized by intracellular arabino-franosidase and xylosidase into arabinose and xylose. | Arabinose and xylose | 87 |
| YIT 13060 | 2ʼ-FL, lacto-N-difucohexaose (LNDFH) | 2ʼ-FL and LNDFH are translocated intracellularly and further degraded in cooperation with fucosidase, β-galactosidase, and Lacto-N-biosidases. | GLcNAC, fucose, galactose, and glucose | 87 |