Diversity in the gut

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The paper:

The finding:

David Relman from Stanford University and colleagues sequenced more than 13,000 ribosomal RNA genes from microbial populations in the gut tissue and feces of three adult humans. "In some ways, this was just an environmental survey asking 'who's there?' in the gut," because previous cultivation-based methods were "not sensitive enough," Relman says. Of the 395 bacterial phylotypes identified, about 80% represented sequences from species that had never been cultivated from human intestinal flora.

Why it was cited:

This study showed "that there are many more bacteria [in the gut] than we had previously known," says Balakrishnan Ramakrishna of Christian Medical College in Vellore, India. Martin Blaser of New York University says he found the statistical methods in the paper useful for comparing microbe populations on different areas of human skin.

The catch:

The study "used a very limited number of people," but the people were intensively studied, Blaser says. Relman says it was interesting to find that each person had a distinct set of individual bacteria.

The next step:

"We're still woefully ignorant" about the diversity of bacteria in the human body, Relman says. His group is surveying microbial populations in the mouth and small intestine of adults. They also are looking at the colonization of microbes during the first year of life, he says.