Gut Microbiota Composition and Activity in Relation to Host Metabolic Phenotype and Disease Risk  Elaine Holmes, Jia V. Li, Julian R. Marchesi, Jeremy K. Nicholson  Cell Metabolism  Volume 16, Issue 5, Pages 559-564 (November 2012) DOI: 10.1016/j.cmet.2012.10.007 Copyright © 2012 Elsevier Inc. Terms and Conditions

Figure 1 Metabolic Axes between Host and the Gut Microbiota (A) Schematic showing some of the major metabolites involved in host-microbe communication, originating from synthesis from microbial conversion of nutrients and host metabolites in the gut lumen and their subsequent transport and interaction with other organs throughout the body. Metabolic axes of host-microbe communication include neurotransmitters such as 5-hydroxyindole and certain biogenic amines; short-chain fatty acids that contribute to energy metabolism in a range of organs and tissues; branched chain amino acids; phospholipid metabolites and bacterial products of choline degradation, e.g, trimethylamine-N-oxide, which has been associated with cardiovascular disease (Wang et al., 2011); triglycerides and fatty acids; microbiota-produced vitamins (e.g., vitamin K); and cometabolites of phenolics and aromatic acids such as 4-cresyl sulfate and hippurate. (B) The phylogenetic arrangement of members of the genera Prevotella, Bacteroides, and Escherichia/Shigella using the 16S rRNA gene as the taxonomic discriminator. (C) A principal component analysis of genomes from the Integrated Microbial Genomes database, using the COG functions to cluster the organisms. The three clusters highlighted are those that include the Bacteroidetes and Prevotella (cluster 1); Enterobacteriaceae (cluster 2); and Firmcutes, Ruminococci, and Actinobacteria (cluster 3). Cell Metabolism 2012 16, 559-564DOI: (10.1016/j.cmet.2012.10.007) Copyright © 2012 Elsevier Inc. Terms and Conditions