The paper:

C. Palmer et al., “Development of the human infant intestinal microbiota,” PLoS Biol, 5:1556–63, 2007. (Cited in 101 papers)

The finding:

Chana Davis and her team at Stanford University School of Medicine designed a microarray to sequence small subunit ribosomal RNA (SSU rRNA) from microbes present in more than 400 excrement samples from 14 healthy infants, starting with the first excrement after birth, to map out normal development of the gut ecosystem. They found that each individual infant had a unique microbial ecosystem that varied over time but remained distinct from other infants’. A pair of fraternal twins had gut environments that remained remarkably similar to each other over time, indicating the strong impact of environment.

The unexpected:

“We were surprised to find that each individual is really unique. There is no average baby,” says Davis (née Palmer).

The impact:

“This paper is one of the first and one of the best examples of using a new genomic technology [microarray] to simultaneously characterize many microbial samples over an extended time course,” says Jonathan Eisen, a geneticist at the University of California, Davis.

The follow-up:

More research has illustrated the role gut microbes play in disease and metabolism, such as a person’s predisposition to obesity (Nature, 457:480–84, 2009).

Bacterial breakdown in samples:
Phylum	Number of Sequences	Relative Abundance
Proteobacteria	1,590	46.14%
Firmicutes	1,103	32.01%
Bacteroidetes	692	20.08%
Actinobacteria	44	1.28%
Verrucomicrobia	15	0.44%
Fusobacteria	2	0.06%

This is great work!

I would be curious to see the difference between nursing and bottle fed flora.

I see this as a great diagnostic tool of the future since 70% of the immune system is in the digestive tract.

Also can this method of identification work on viruses?

Fascinating - the article does this story an injustice. More information about the relative merits of the study should have been discussed.