In your body there are 10 times more microbes than your own human cells. A billion more microbes live on Earth than there are stars in the known universe.
Biologists are confident in estimating the terrestrial total at about a nonillion of individual microbes – that is 10 with 30 zeros after it. Most are bacteria but no one has a good idea how many species or strains there are, or how these are distributed around the world. Only a minute fraction of microbial species have been characterised or cultured in the lab.
Now, scientists armed with the latest gene sequencing technologies are embarking on the first systematic attempt to measure the diversity of microbial life. The Earth Microbiome Project is an international collaboration based at Argonne National Laboratory outside Chicago.