Evolution of Symbiotic Bacteria in the Distal Human Intestine

http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0050156

The adult human intestine contains trillions of bacteria, representing hundreds of species and thousands of subspecies.

Little is previous known about the selective pressures that have shaped and are shaping this community's component species, which are dominated by members of the Bacteroidetes and Firmicutes divisions.

We sequenced the genomes of two members of the normal distal human gut microbiota, Bacteroides vulgatus and Bacteroides distasonis, and by comparison with the few other sequenced gut and non-gut Bacteroidetes, analyzed their niche and habitat adaptations.

The results show that lateral gene transfer, mobile elements, and gene amplification have played important roles in affecting the ability of gut-dwelling Bacteroidetes to vary their cell surface, sense their environment, and harvest nutrients in the distal intestine.

These processes drive the adaptation of Bacteroidetes to the distal gut environment.