We're Never Alone

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Science  22 Feb 2008:
Vol. 319, Issue 5866, pp. 1013
DOI: 10.1126/science.319.5866.1013c

Each of us carries a community of microorganisms in our intestinal tract that is necessary for optimal health but varies in composition from person to person. To learn which gut microbes most influence human physiology, Li et al. surveyed these symbionts in seven members of a four-generation Chinese family. By sequencing rRNA genes, they assembled a phylogenetic picture of the resident microbes-mainly Bacteroidetes and Firmicutes spp. The Chinese microbiomes showed individual and male/female differences in their composition, although all differed markedly from those seen in Americans. A parallel analysis of urine samples from the same family allowed the authors to correlate variations in resident microbes with variations in excreted metabolites, which served as a proxy for the individuals' metabolic state. They found several microbial species that appeared to significantly affect their hosts: for instance, Faecalibacterium prausnitzii was associated with the presence of dimethylamine, suggested to be an indicator of metabolic syndrome and diabetes. This functional metagenomics approach can be extended by combining full genomic sequencing of the microbes with measurements of metabolic or clinical features of interest. Ultimately, the hope is to identify which gut inhabitants are associated with disease states and which with human well-being. — KK

Proc. Natl. Acad. Sci. U.S.A. 105, 2117 (2008).

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