The findings may help researchers learn more about steering infants' immune development away from inflammatory, allergy-prone pathways.

We each have trillions of microbial hitchhikers living in and on our bodies. These symbiotic organisms have co-evolved with us over millions of years and increasingly are being seen as essential to our health and well being, researchers said at the 2012 Abelson Symposium at AAAS.

The effort to understand the human microbiome—the full complement of 4 million or more genes contained in the microbial community we each harbor—is one of the hottest fields of scientific research.