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Same research study is discussed as in the last post (Your Bacteria All Over Your Home), but different write-up with more and different details. From Washington Post:

Hotel rooms aren’t yucky – you colonize them with your own personal bacteria within hours

When you move from one house to another, you take all your bacteria with you. In fact, your family's microbiome (or your eco-system of inner and outer bacteria) lays claim to hotel rooms with hours. Our bacterial signatures are so persistent and so unique, a new study published Thursday in Science reports, that they could even be used in forensic investigations — and eventually become more useful to police than an old-fashioned fingerprint. And the same research that could track down a serial killer could also help you raise healthier kids.

In studying seven families as they moved from one house to another, the microbiologists had one major takeaway: Bacteria move from your body to your living space at incredible speed.

"Everyone thinks hotels are icky," said Jack Gilbert,, corresponding author of the study and environmental microbiologist at Argonne National Laboratory, "but when one young couple we studied moved into a hotel, it was microbiologically identical to their home within 24 hours." And unpublished further research reveals that the time frame is even swifter than that. "No matter what you do to clean a hotel room," Gilbert said, "your microbial signal has wiped out basically every trace of the previous resident within hours."

What's more, the researchers were able to determine how much individuals in a family interacted, what rooms they used, and even when they'd last been to one part of the house or another. This has obvious applications in forensic science. "We could go all J. Edgar Hoover on this and make a database of microbial fingerprints of people all over the world," Gilbert said, "and it's far more sophisticated than a standard fingerprint, which is just a presence or absence indication. We can see who they are, where they're from, the diet they're eating, when they left, who they may have been interacting with. It gets pretty crazy."

Gilbert and his colleagues are already working with police in Hawaii, hoping to look at the microbiome left on dead bodies. "If someone is, shall we say, recently and inappropriately deceased," Gilbert said, "we can look at their bacterial colonies and try to identify who the last person to come into contact with them was, and when." Based on some promising animal studies, he said, it could be possible. "An actual fingerprint is rarely left on a body," Gilbert said, "but a microbial fingerprint certainly is."

The Home Microbiome Study has more immediate applications, too. Gilbert, a father of two, hopes that fellow parents will use these and future findings to raise their offspring in healthier microbiomes. Before the age of two, the human microbiome remains in flux. Different species of bacteria compete to gain permanent spots — and once the race is run, you're basically stuck with the winners. Research in animals has shown that bacterial exposure in youth can impact physical and mental development and health for the rest of an organism's life.

"Let's say a kid grows up in an apartment block, without going outside much," Gilbert said. "They're just getting this same human bacteria fed back to them, day after day." More exposure is most certainly the better route.

For starters, get a dog. Partway through the study, Gilbert did just that. "We saw dogs acting as a super-charged conduit," he said, "transferring bacteria between one human and another, and bringing in outdoor bacteria. They just run around distributing microbes all willy-nilly." Sure enough, his family saw their home's microbiome benefit from the new addition.

We now know that most bacteria are beneficial to us — and that some can even prevent allergies."Imagine if we could engineer our home environments, optimize our carpeting and air conditioning systems, to bring in the really good bacteria," he said. 

Exciting research! From Science Daily:

Home is where the microbes are

A person's home is their castle, and they populate it with their own subjects: millions and millions of bacteria. Scientists have detailed the microbes that live in houses and apartments. The study was conducted by researchers from the U.S. Department of Energy's Argonne National Laboratory and the University of Chicago. 

The results shed light on the complicated interaction between humans and the microbes that live on and around us. Mounting evidence suggests that these microscopic, teeming communities play a role in human health and disease treatment and transmission.

"We know that certain bacteria can make it easier for mice to put on weight, for example, and that others influence brain development in young mice," said Argonne microbiologist Jack Gilbert, who led the study. "We want to know where these bacteria come from, and as people spend more and more time indoors, we wanted to map out the microbes that live in our homes and the likelihood that they will settle on us.

The Home Microbiome Project followed seven families, which included eighteen people, three dogs and one cat, over the course of six weeks. The participants in the study swabbed their hands, feet and noses daily to collect a sample of the microbial populations living in and on them. They also sampled surfaces in the house, including doorknobs, light switches, floors and countertops. Then the samples came to Argonne, where researchers performed DNA analysis to characterize the different species of microbes in each sample.

They found that people substantially affected the microbial communities in a house -- when three of the families moved, it took less than a day for the new house to look just like the old one, microbially speaking.

Regular physical contact between individuals also mattered -- in one home where two of the three occupants were in a relationship with one another, the couple shared many more microbes. Married couples and their young children also shared most of their microbial community.

Within a household, hands were the most likely to have similar microbes, while noses showed more individual variation. Adding pets changed the makeup as well, Gilbert said -- they found more plant and soil bacteria in houses with indoor-outdoor dogs or cats.

In at least one case, the researchers tracked a potentially pathogenic strain of bacteria called Enterobacter, which first appeared on one person's hands, then the kitchen counter, and then another person's hands. "It's also quite possible that we are routinely exposed to harmful bacteria -- living on us and in our environment -- but it only causes disease when our immune systems are otherwise disrupted."

Home microbiome studies also could potentially serve as a forensic tool, Gilbert said. Given an unidentified sample from a floor in this study, he said, "we could easily predict which family it came from."

The research also suggests that when a person (and their microbes) leaves a house, the microbial community shifts noticeably in a matter of days."You could theoretically predict whether a person has lived in this location, and how recently, with very good accuracy," he said.