The bacteria that we keep on and inside of our bodies can uniquely identify people, like their fingerprints, according to new research.

The study is the first to suggest that the community of bacteria, known as the microbiome, could feasibly be used to identify people. The researchers also say that it could lead to privacy concerns for those involved in projects to study the microbiome, since they may be unknowingly giving up uniquely identifying data.

Scientists are studying the human microbiome with the hope that it can be used to spot and treat specific problems. It is a relatively new area of study.

Researchers made the discovery about the uniqueness of the microbiome by looking through data produced by the Human Microbiome Project, which collected bacteria from different parts of the body of 242 subjects. They then used an algorithm to calculate the bacteria into “codes”, which they could compare with peoples’ bacteria over time as well as with other people.

The study found that the codes were unique among those studied, and that the codes tended to stay stable over the one-year period that they were sampled for. Gut samples, which stayed especially stable, didn’t change in 80 per cent of cases.

“Linking a human DNA sample to a database of human DNA 'fingerprints' is the basis for forensic genetics, which is now a decades-old field,” Eric Franzosa, the leader author of the study, told Phys.org. “We've shown that the same sort of linking is possible using DNA sequences from microbes inhabiting the human body—no human DNA required.