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Metabolism of hydrogen gases and bile acids in the gut microbiome
Author(s) -
Hylemon Phillip B.,
Harris Spencer C.,
Ridlon Jason M.
Publication year - 2018
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.13064
Subject(s) - acetogenesis , bile acid , metabolism , microbial metabolism , biochemistry , chemistry , microbiome , chenodeoxycholic acid , carbon dioxide , bacteria , microbiology and biotechnology , biology , methanogenesis , methane , organic chemistry , bioinformatics , genetics
The human gut microbiome refers to a highly diverse microbial ecosystem, which has a symbiotic relationship with the host. Molecular hydrogen (H 2 ) and carbon dioxide (CO 2 ) are generated by fermentative metabolism in anaerobic ecosystems. H 2 generation and oxidation coupled to CO 2 reduction to methane or acetate help maintain the structure of the gut microbiome. Bile acids are synthesized by hepatocytes from cholesterol in the liver and are important regulators of host metabolism. In this Review, we discuss how gut bacteria metabolize hydrogen gases and bile acids in the intestinal tract and the consequences on host physiology. Finally, we focus on bile acid metabolism by the Actinobacterium Eggerthella lenta . Eggerthella lenta appears to couple hydroxyl group oxidations to reductive acetogenesis under a CO 2 or N 2 atmosphere, but not under H 2 . Hence, at low H 2 levels, E. lenta is proposed to use NADH from bile acid hydroxyl group oxidations to reduce CO 2 to acetate.