The human body is only one percent human, microbiologists like to say. Each of us plays host to an ecosystem of thousands of species of bacteria, fungi, parasites, and viruses that amount to trillions of microorganisms. Together these compose our microbiome. If you factor in their total genomic content as part of our own, we are 99 percent microbial.
Over the last decade and half, there’s been what Dr. Andrew Koh, a professor of pediatrics and microbiology at UT Southwestern Medical Center in Dallas, calls a “microbiome explosion,” a tremendous increase in research and commercial interest in understanding and manipulating how our microbiome affects our health. The greatest number of microorganisms live in our intestines, but they can be found throughout the body, and they play a major role in our immune system. A host of conditions, ranging from irritable bowel syndrome to depression, has been explored in