Science, Vol 308, Issue 5728, 1635-1638, 10 June 2005

Diversity of the Human Intestinal Microbial Flora
Paul B. Eckburg, Elisabeth M. Bik, Charles N. Bernstein, Elizabeth Purdom, Les
Dethlefsen, Michael Sargent, Steven R. Gill, Karen E. Nelson, David A. Relman1

The human endogenous intestinal microflora is an essential "organ" in providing
nourishment, regulating epithelial development, and instructing innate
immunity; yet, surprisingly, basic features remain poorly described. We
examined 13,355 prokaryotic ribosomal RNA gene sequences from multiple colonic
mucosal sites and feces of healthy subjects to improve our understanding of gut
microbial diversity. A majority of the bacterial sequences corresponded to
uncultivated species and novel microorganisms. We discovered significant
intersubject variability and differences between stool and mucosa community
composition. Characterization of this immensely diverse ecosystem is the first
step in elucidating its role in health and disease.

Tom Billings