Hard to digest

摘要

Bacteria, like people, can be divided into friend and foe. Inspired by evidence that the friendly sort may help with a range of ailments, many people consume bacteria in the form of yogurts and dietary supplements. Such a smattering of artificial additions, however, represents but a drop in the ocean. There are at least 800 types of bacteria living in the human gut. And research by Steven Gill of the Institute for Genomic Research in Rockville, Maryland, and his colleagues, published in this week's Science, suggests that the collective genome of these organisms is so large that it contains 100 times as many genes as the human genome itself.