A team of researchers at Washington University in St. Louis has characterized the human gut microbiome by sequencing the microbial communities of adult twins and their mothers. They report that the study invalidated the hypothesis that a uniform human gut microbiome exists at the level of bacterial species. Instead, the results demonstrated that common metabolic functions yield a gut microbiome that is carried out by communities varying greatly in exact species composition across individuals.
When comparing lean and obese twins, the researchers found further that deviations from this core functional microbiome were associated with the differences in physiologic states. The study also revealed significant differences in genes associated with nutrient metabolism.
Using the Genome Sequencer FLX System, the investigators found that individuals from the same family had more similar bacterial communities than unrelated individuals. The immense microbial diversity found across all individuals forced them to reconsider the hypothesis of a core microbiome based on the relative abundance of bacterial families. Instead, common functional categories of genes and metabolic pathways were consistently found across all samples, implying that a variety of bacterial species can perform the same metabolic functions.
The article appears online in the November 30 issue of Nature.