GL: Does each home have its own microbial signature?
NF: That's what we're studying now. We're sampling 1,000 homes across the U.S. to get at questions like, how different are individual homes? Does it matter if you live in a humid environment versus an arid one? If you have dogs in the house, does that affect the types of microbe in your home, or if you're vegetarian? Are there different microbes if you live in a forest or a city? These are big, basic questions that we don't yet know the answers to.
GL: Do you have any understanding of how the ecosystems function? Are there food webs?
NF: There's undoubtedly a food web, though we don't know much about it yet. There are fungi and bacteria that feed the mites and so forth, and it's interesting to think of our homes as mini-ecosystems, as places where microbes move around, reproduce, and are consumed.
GL: Have you looked at workplaces too?
NF: Indirectly. We looked at bacteria on computer keyboards a few years ago, and basically showed that you could match the bacteria on your fingertips to those on your keyboard.
GL: Why should we care about these microbes, beyond the curiosity value?
NF: It is likely that they influence our health—many of these microbes may be triggers of allergies and asthma. There is also the issue of food spoilage. And smells. Everybody's home has a slightly different smell and part of that is driven by microbes.
There are these practical applications, but that's like asking why early biologists cruised around the world studying plants. The first step is to see what's out there.
GL: Is there a forensic application?
NF: Can you identify the likely occupants of a house from its microbes? Can you tell if the previous owners had pets, for example? It's too early to say, but the fact that we've demonstrated that we can match bacteria on a keyboard to those on your fingers shows we might be able to find out much more and predict how building materials, design, and the specific inhabitants of a house alter the microbial life found within.
We have hundreds of different bacteria just on the palms of our hands and each of these signatures is unique. We leave bacteria on everything we touch. But we need to do more work to establish how long bacteria persist on different surfaces, like metal, cloth, and plastic, and to study surfaces that are touched by several people.
GL: Does knowing what is living on your cutting board or in your bathroom change your behavior? Are you obsessed with cleaning?
NF: No! I think you can put microbiologists into two categories. There are those that are paranoid about microbes because they know how many are out there and that we're constantly coming into contact with them. Then there are those like me who are like, well, they're everywhere, in everything we eat and every surface we touch, so let's not worry too much.
This article originally ran in New Scientist.