Bifidobacterium shunt
Pathway
Source
Taxonomic Scope
conserved
Category
pathway
Dates
- Create:2019-01-17
- Modify:2022-05-18
Description
The first to isolate a Bifidobacterium was Tissier of the Pasteur Institute in France, who in 1899
isolated an organism from a breast-fed infant [Tissier00]. He named the organism
TAX-1681, describing the branching morphology of the bacteria (bifidus in Latin
means forked or split into two parts). However, in the 1960s Bifidobacterium was accepted as an
independent genus, and today more than 30 species are documented [PMID: 15539925].
Bifidobacteria are accepted as important probiotic components of the human intestinal microflora,
and are used in health-promoting foods [15916644][16167966].
The Bifidobacteria use a unique pathway of hexose catabolism, which produces primarily acetate and
lactate.
This fermentation pathway, which is known as the "Bifidobacterium shunt" or the
"fructose-6-phosphate pathway" yields 3 mols of acetate and 2 mols of lactate for 2 mols of glucose,
with production of 5 mols of ATP [6020562][6048259][4236541][9430608].
The key enzyme in the pathway is CPLX-7204, which catalyzes two important steps:
splitting FRUCTOSE-6P into ERYTHROSE-4P and ACETYL-P, and
splitting XYLULOSE-5-PHOSPHATE into GAP and ACETYL-P.
This enzyme has often been used as a tool in the identification of Bifidobacteria [PMID: 11298932],
even though such enzymes have been found in other organisms.
Acetylphosphate, which is formed in both phosphoketolase-catalyzed steps, is converted to ACET.
ERYTHROSE-4P is processed along with a second FRUCTOSE-6P molecule by
enzymes of the PENTOSE-P-PWY to XYLULOSE-5-PHOSPHATE. This compound
is then split in the second reaction catalyzed by phosphoketolase to GAP and
ACETYL-P. GAP is processed via the glycolytic Embden-Meyerhof pathway to
PYRUVATE, which is subsequently converted to L-LACTATE.
- BioCycLICENSEIncludes BioCyc pathway/genome databases under license from SRI Internationalhttps://bioinformatics.ai.sri.com/ptools/licensing/all-reg.shtml
- PubChem
CONTENTS