Helpful Bacteria

Scientists are even discovering ecosystems in our bodies where they weren’t supposed to exist. Lungs have traditionally been considered to be sterile because microbiologists have never been able to rear microbes from them. A team of scientists at Imperial College London recently went hunting for DNA instead. Analyzing lung samples from healthy volunteers, they discovered 128 species of bacteria. Every square centimeter of our lungs is home to 2,000 microbes.

In addition to helping us digest, the microbiome helps us in many other ways. The microbes in our nose, for example, make antibiotics that can kill the dangerous pathogens we sniff. Our bodies wait for signals from microbes in order to fully develop. When scientists rear mice without any germ in their bodies, the mice end up with stunted intestines.

In order to co-exist with our microbiome, our immune system has to be able to tolerate thousands of harmless species, while attacking pathogens. Scientists are finding that the microbiome itself guides the immune system to the proper balance.

http://www.nytimes.com/2010/07/13/science/13micro.html?_r=1&pagewanted=all