You probably don’t like to think about it, but the human body hosts an unbelievable number of bacteria and other single-celled organisms, from the gut to the lungs to the skin, and plenty of places in between. In fact, some estimates hold that our microbial population outnumbers our body’s own cells by a factor of ten to one.
Whether or not that gives you the yucks, scientists are gearing up to begin exploring what they call the “microbiome” in earnest. I stumbled across this notion on Epidemix, where Tom Goetz notes a recent talk by UC Davis evolutionary biologist Jonathan Eisen about a new effort to sequence the genomes of all these little beasties, a project the NIH is calling the Human Microbiome Project.
(One representative microbiome member, the friendly — and sometimes not-so-friendly — bacterium E. coli, is featured above.) The goal is essentially to finally start piecing together a coherent picture of our closest friends and neighbors — literally — and the role they play in human health and disease.
If you’re put off by the NIH page and are interested in learning more, there’s a somewhat more accessible Eisen post on the subject here. This Wikipedia article isn’t a bad resource, either. In any case, this sort of project does seem enormously cool. Sure, anyone who’s ever read the label on a yogurt container probably knows that stuff lives in our gut, but we know surprisingly little about our intestinal pets and the degree to which they actively improve our lives as opposed to merely coexisting with us.
One interesting concept I hadn’t encountered before stumbling across this discussion is that of “metagenomic analysis,” which essentially boils down to sequencing a bunch of organisms taken straight from their natural environment, as opposed to those that have been growin in a lab. It’s a much messier process — the virtue of sequencing a microbe colony that grew from a single cell is that you know all members are genetically identical, which is most emphatically not the case in environmental samples — but it gives you a much better sense of what’s actually going on in nature. Or, you know, in your large intestine.