When you move into a new home, you might personalize it with your favorite paint color, different furnishings, and familiar knick-knacks. Research recently published in the journal Science indicates that redecoration extends to bacteria as well. After a few days, surfaces in a home begin to take on the distinct signature of a new resident’s microbiome—that is, the collection of bacteria that live on and in a person’s body. Jack Gilbert, an environmental microbiologist at Argonne National Laboratory and lead author of the study, is trying to develop a better understanding of the way people, bacteria, and the environment around them interact, from the kitchen floor to the greater Chicago area.