Your home life is more crowded than you think.

A new study has found that people have their own unique blend of bacteria on their bodies and in their homes.

The study called the Home Microbiome Project was done by researchers from the U.S. Department of Energy's Argonne National Laboratory and the University of Chicago. One of the focuses of the study is carefully mapping the interaction between people and the microbes around them.

"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." said Jack Gilbert, who led the study, in a statement. "They are essential for us to understand our health in the 21st century."

The researchers monitored seven families, which included eighteen people, three dogs and one cat, for six weeks. The participants swabbed their hands, feet and noses daily to collect samples of the microbial populations living around them. They also took samples from surfaces inside the house, including doorknobs, light switches, floors and counters. DNA analysis showed the researchers what different species of microbes were thriving in each environment.

"We wanted to know how much people affected the microbial community on a house's surfaces and on each other," Gilbert said. They found that the people were greatly tied to the microbial communities in their home. When three families moved, after less than a day the new house had microbes that mirrored those in the old house.

Interestingly, this may mean that home microbiome studies could serve as a forensic tool. For instance, if a person eaves a house, the microbial community changes in a matter of days. "You could theoretically predict whether a person has lived in this location, and how recently, with very good accuracy," Gilbert said.

The paper, "Longitudinal analysis of microbial interaction between humans and the indoor environment," was published in the journal Science. It was authored by Simon Lax, Daniel P. Smith, Jarrad Hampton-Marcell, Sarah M. Owens, Kim M. Handley, Nicole M. Scott, Sean M. Gibbons, Peter Larsen, Benjamin D. Shogan, Sophie Weiss, Jessica L. Metcalf, Luke K. Ursell, Yoshiki Vázquez-Baeza, Will Van Treuren, Nur A. Hasan, Molly K. Gibson, Rita Colwell, Gautam Dantas, Rob Knight and Jack A. Gilbert.

Photo: Diana Parkhouse