992 VEGETARIAN DIET REDUCES HUMAN GUT MICROBIAL TMAO PRODUCTIVITY THROUGH ALTERATIONS OF GUT MICROBIOME IN PATIENTS WITH CARDIOVASCULAR DISEASE

2020 ◽  
Vol 158 (6) ◽  
pp. S-196
Author(s):  
Wei-Kai Wu ◽  
Chieh-Chang Chen ◽  
Po-Yu Liu ◽  
Suraphan Panyod ◽  
Cheng-Chih Hsu ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
Gut Microbiome ◽  
Vegetarian Diet ◽  
Human Gut

scholarly journals MtcB, a member of the MttB superfamily from the human gut acetogen Eubacterium limosum, is a cobalamin-dependent carnitine demethylase

2020 ◽  
Vol 295 (34) ◽  
pp. 11971-11981 ◽  
Author(s):  
Duncan J. Kountz ◽  
Edward J. Behrman ◽  
Liwen Zhang ◽  
Joseph A. Krzycki
Keyword(s):  
Cardiovascular Disease ◽  
Gut Microbiome ◽  
Health Benefits ◽  
Perceived Health ◽  
Biological Product ◽  
Human Gut ◽  
Methyl Donor ◽  
Eubacterium Limosum ◽  
Related Proteins ◽  
Acetate Butyrate

The trimethylamine methyltransferase MttB is the first described member of a superfamily comprising thousands of microbial proteins. Most members of the MttB superfamily are encoded by genes that lack the codon for pyrrolysine characteristic of trimethylamine methyltransferases, raising questions about the activities of these proteins. The superfamily member MtcB is found in the human intestinal isolate Eubacterium limosum ATCC 8486, an acetogen that can grow by demethylation of l-carnitine. Here, we demonstrate that MtcB catalyzes l-carnitine demethylation. When growing on l-carnitine, E. limosum excreted the unusual biological product norcarnitine as well as acetate, butyrate, and caproate. Cellular extracts of E. limosum grown on l-carnitine, but not lactate, methylated cob-(I)alamin or tetrahydrofolate using l-carnitine as methyl donor. MtcB, along with the corrinoid protein MtqC and the methylcorrinoid:tetrahydrofolate methyltransferase MtqA, were much more abundant in E. limosum cells grown on l-carnitine than on lactate. Recombinant MtcB methylates either cob(I)alamin or Co(I)-MtqC in the presence of l-carnitine and, to a much lesser extent, γ-butyrobetaine. Other quaternary amines were not substrates. Recombinant MtcB, MtqC, and MtqA methylated tetrahydrofolate via l-carnitine, forming a key intermediate in the acetogenic Wood–Ljungdahl pathway. To our knowledge, MtcB methylation of cobalamin or Co(I)-MtqC represents the first described mechanism of biological l-carnitine demethylation. The conversion of l-carnitine and its derivative γ-butyrobetaine to trimethylamine by the gut microbiome has been linked to cardiovascular disease. The activities of MtcB and related proteins in E. limosum might demethylate proatherogenic quaternary amines and contribute to the perceived health benefits of this human gut symbiont.

Methotrexate-Induced Shifts in the Human Gut Microbiome Decrease Immune Activation

2020 ◽  
Author(s):  
Renuka R. Nayak ◽  
Margaret Alexander ◽  
Ishani Deshpande ◽  
Kye Stapleton-Grey ◽  
Carles Ubeda ◽  
...  
Keyword(s):  
Immune Activation ◽  
Gut Microbiome ◽  
Human Gut ◽  
Human Gut Microbiome

scholarly journals Taxonomic signatures of cause-specific mortality risk in human gut microbiome

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Aaro Salosensaari ◽  
Ville Laitinen ◽  
Aki S. Havulinna ◽  
Guillaume Meric ◽  
Susan Cheng ◽  
...  
Keyword(s):  
Mortality Risk ◽  
Gut Microbiome ◽  
Human Gut ◽  
Cross Sectional ◽  
Microbiome Composition ◽  
Human Gut Microbiome ◽  
Non Invasive ◽  
Sequencing Technologies

AbstractThe collection of fecal material and developments in sequencing technologies have enabled standardised and non-invasive gut microbiome profiling. Microbiome composition from several large cohorts have been cross-sectionally linked to various lifestyle factors and diseases. In spite of these advances, prospective associations between microbiome composition and health have remained uncharacterised due to the lack of sufficiently large and representative population cohorts with comprehensive follow-up data. Here, we analyse the long-term association between gut microbiome variation and mortality in a well-phenotyped and representative population cohort from Finland (n = 7211). We report robust taxonomic and functional microbiome signatures related to the Enterobacteriaceae family that are associated with mortality risk during a 15-year follow-up. Our results extend previous cross-sectional studies, and help to establish the basis for examining long-term associations between human gut microbiome composition, incident outcomes, and general health status.

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