Your home’s microbiome, revealed

Here’s what you need to know about the bacteria, fungi, and viruses in your house.

cleaning a home
Anywhere life exists, so do microbes, and every environment—even the International Space Station—has its own microbiome.Deposit Photos

There’s a whole world unfolding in your house, and one that you’ll never see: the life of your home’s microbiome. This complicated little universe of bacteria, fungi, viruses, and other microbes is on every surface and even in the air you breathe. But unlike your pipes, lights, and appliances, this microscopic ecosystem keeps itself running—as long as we don’t meddle too much with it.

Microbiome might sound like a fancy term, but it’s pretty easy to understand. “A microbiome is a collection of all the microbes within a specific environment,” explains Northwestern University microbiologist Erica Hartmann. You’ve probably heard the term before in reference to your own body’s gut microbes. But anywhere life exists, so do microbes, and every environment—even the International Space Station—has its own microbiome.

Don’t freak out. While bacteria, viruses, and other tiny organisms often get a bad rap for causing infectious diseases, microbes are not inherently bad. “In general, the fact that your home has a microbiome is not a harmful thing,” she says. “There’s a microbiome everywhere.” Most of the microbes in your home can’t make you sick and they fill environmental niches that could otherwise be taken over by ones that *can* cause disease. And since the more enclosed an environment is, the higher the probability it will transfer microbes to you, avoiding those pathogens is especially important in an indoor environment where you spend a lot of time.

Microbes come from a variety of sources: There are the ones that live on you and your family all the time, the organisms that hitchhike a ride in from outside, your pets’ microbes, and the tiny bugs that live on the stuff in your home. That includes everything from your sink to your dusty ceiling fan and even the air.

While scientists know our homes are teaming with resident microbes, they know far less about what types are there or which ones are most common.That’s because scientists are still figuring out how to identify and count all the microbes in a microbiome, says Hartmann. For one thing, the organisms can only be seen under a microscope—and viruses require even more specialized kinds of microscopes, because they are between 100 and 500 times smaller than bacteria. Homes are also often big and diverse so quantifying all the microbes in each one would take a very long time.

Scientists are working hard to understand your home’s microbiome, though. And that’s for good reason: The microbes in homes are well-positioned to evolve and adapt such that our defenses against more dangerous microbes could shift. To study the bugs, researchers swab various home surfaces and then sequence all the DNA present on the swab. That DNA often comes from a variety of microbial sources—those viruses, bacteria, and fungi mentioned up top as well as archaea, which are microorganisms similar to bacteria—and of course larger sources like humans and their pets. By zeroing in on the microbial DNA and identifying the exact species, scientists can get a sense of your home’s microbiome and who is part of it.

Around the world, scientists have found, home microbiomes are very diverse. Hartmann recently worked on a study that aggregated all kinds of bacteria found in homes during previous studies. Where a home is located, who lives in it, and the prevailing conditions inside the home (such as how moist it is) all affect the home’s microbiome, she found.

At this point, though, Hartmann says you don’t need to think about any of this. “I’m not sure what you would do with that information,” she says. But she and other scientists still want to understand the home microbiome and the role it plays in the world of microbes.

Her recent study’s overall aim was to look at how microbes in a home environment contribute to the rise of antibiotic-resistant superbugs. All the microbes in your home plus all the cleaners and medications in your home creates the circumstances for microbes to evolve to become more resistant. Antimicrobial resistance is bad news for many reasons. It affects human health, making treatments for certain infectious diseases less effective, it affects our food supply, because more pathogenic bugs kill more livestock, and it affects the natural world.

You can help with this issue. In your home, you can fight antibiotic resistance by asking your doctor if antibiotics are really needed for what’s ailing you and avoiding things like antibacterial hand soap and cleaners unless they are absolutely necessary (as they wipe out both good and bad bacteria in one sweep).

So, how should you keep your house free from any dangerous microbes that might make you sick, but still keep the good bugs? Since standing water has the potential to harbor microbes, a good policy, generally, is to avoid having it around. Keeping things as dry as possible is generally a good idea. Researchers have found that replacing your kitchen sponge weekly, for example, and regularly washing your kitchen towels–two things that are regularly damp and which touch both you and your food often—is a good way to prevent the growth of microbes that might cause human disease.

If you are still burning with curiosity about what might be living in your home, Hartmann suggests checking out Community of Microbes, an app and website created by an artist and a microbiologist that tells you more about the different kinds of microbes living in your environment. And be a good roommate: Stay away from antibacterial hand soap.