

When astronomers talk about the number of planets in the Milky Way Galaxy, they talk in terms of hundreds of billions. When microbiologists talk about the Human Microbiome — the bacteria, viruses and fungi living in and on each of our bodies — they talk in terms of hundreds of trillions.

Earlier this month, the Human Microbiome Project published the most extensive investigation on the human microbiome to date. And now, we have the clearest picture ever of the microorganisms that call you home — and this knowledge is likely to affect your life in ways you'd never expect. Here are 10 ways that understanding the organisms inside you could change science and medicine forever.

10. Your medical records will list your enterotype
Much like there are eight different common blood types, researchers announced last year the existence of at least three distinct human "enterotypes", or intestinal bacterial communities. Each enterotype is characterized by the predominance of one of three genera: Bacteroides, Prevotellaor or Ruminococcus. Incredibly, the researchers found no link between enterotype and age, nationality, gender, body weight, or even overall health.



9. But enterotypes are just the beginning
Remember: "enterotype" refers solely to the microbiota of the gut, but your microbiome extends throughout and over your entire body. Doctors could therefore consider more than just your enterotype when consulting your medical records; they could reference a much larger picture — one that encapsulates the various ecosystems that support your entire body.

The phylogenetic tree featured here, for example (borrowed from this outstanding New York Times feature) gives an overview of the microbes found in or on human ears, vaginas, noses, tongues, teeth and cheeks. Your body is a whole wide world universe of microbial life.

8. Doctors could use your microbiome to custom tailor medical treatments
And yet, every person's microbial universe is different; for example, a bacterium that dominates the ecosystem of one person's mouth can be missing entirely from someone else's. Researchers suspect that the differences in our microbial makeups could allow doctors to custom tailor their diagnoses and treatments. The potential for personalized medicine could be huge.

7. Treat the microbiome by fortifying its allied forces
A person with a bacterial infection in her gut could be said to be in possession of an out-of-balance bacterial ecosystem; somewhere in her intestines, a rebel faction of bacteria is wreaking havoc. One potential form of therapy: manipulate the dynamics of said ecosystem by pitting one (or several) species of virus, bacterium or fungus against another.

A more intimate understanding of the microbiome will allow us to understand how microbial species interact to maintain a healthy, balanced environment (be it in your mouth, your gut, or on the surface of your skin), and how to fix that balance when things get thrown off kilter.


6. A solution to the growing problem of antibiotic resistance?
Antibiotic resistance is becoming a more serious issue by the day, due in no small part to the widespread use of broad spectrum antibiotics, which wipe out our bodies' good bugs and bad bugs indiscriminately.

With a greater understanding of the microbiome could come microbe-boosting treatments like the ones mentioned above, providing doctors with powerful (and effective) alternatives to antibiotics. In fact, it's already been shown to work in cases of Clostridium difficile infection. (Note that, because the microbiome comprises not just bacteria, but viruses and fungi, these treatments wouldn't necessarily be limited to probiotics.)

5. An end to the war on germs
By treating our microbiomes like ecosystems — equipping it with the resources it needs to sort itself out rather than attacking it, guns blazing — some researchers hope to usher in a new way of thinking about our relationship with bacteria and other microorganisms.

"I would like to lose the language of warfare," said Julie Segre of the National Human Genome Research Institute in an interview with Carl Zimmer, who has written extensively on the subject of the human microbiome. "It does a disservice to all the bacteria that have co-evolved with us and are maintaining the health of our bodies."


4. Blur the line dividing Humanity from Nature
To quote another, different Zimmer article:


In other words, many of the microorganisms that live in and on our bodies can also be found thriving in nature. Because microbes are continuously entering and leaving your body; in many ways, "your" microbiome, while essential to your individual health, extends beyond the confines of your body. The more we understand about the human microbiome, the more we come to realize that everything is, in fact, like, totally connected, man.

3. Treating one person could affect many
Our microbes connect us all. Since these organisms don't stay confined to any one body, any bugs specifically chosen to treat a person's ailment have the potential to affect those in that person's surroundings, as well. (It's not a perfect analogy, but think of how genetically modified crops are susceptible to spreading to non-GM fields via seed-dispersal). Would roving microbes necessarily be a problem? Doctors aren't sure yet — but they have the potential to raise a number of bioethical concerns.


2. Do you own your microbes?
For instance, here's a great thought experiment, from the same Zimmer article as above:

Imagine a scientist gently swabs your left nostril with a Q-tip and finds... a previously unknown [bacterial species] that produces a powerful new antibiotic. Her university licenses it to a pharmaceutical company; it hits the market and earns hundreds of millions of dollars. Do you deserve a cut of the profits?

We've just discussed how our microbiomes are what connect us all — not just with nature, but with one another. But we've also established that our microbiomes are very much a part of who we are as individuals. The viruses, bacteria and fungi living in your nostrils are very different from the ones living in mine; who's to say the bacterial species that produces this powerful new antibiotic didn't evolve by trading genes with the specific combination of bugs located in your nostrils?

Then again, who's to say they evolved in your nostrils in the first place?

1. Your microbiome profile will be kept private
One way to determine if the bacterial species discovered in your nostril evolved in your nose, specifically, would be to look for it in the noses of everyone else. It sounds like a ridiculous feat because it is. For one thing, it would require for the microbiome of every person on earth to be catalogued in a worldwide database. People would need to have their microbiomes updated on a regular basis to account for shifts in the dynamics of their various corporeal ecosystems. Add to this the fact that the genes of your microbiome are thought to outnumber your own by a hundred to one, and your looking at a logistical nightmare — not to mention a technical impossibility.

And even if such a database did exist, you'd still presumably need permission from every single person on Earth to make any comparisons; many researchers argue that your microbiome, like your genes, should remain private, protected information.

Via The New York Times [1, 2, 3]; Discover; The Scientist
Images via Shutterstock