A new study presented at Pittcon 2018 shows that the microbial communities we carry in and on our bodies—known as the human microbiome—have the potential to identify individuals, much like a fingerprint. The study suggests that we can potentially use this fingerprint in forensic science, but that would be in the distant future.

A microbiome is the sum total of the microbes of bacteria, fungi, and viruses that live inside your body. They are all over your skin and in your gut. Bacteria alone accounts for 2-3 lbs of your body mass. Researchers have been trying to understand if our bacterial signature can act like a fingerprint, and be used as some kind of forensic tool, like trace evidence.

Researchers have been trying to see if the bacterial signature that lives inside the human body is somehow correlated with lifestyle choices. Different working environments can determine what bacteria live inside an individual, how they grow and how they’re distributed, so researchers wanted to see if that correlates.

Th researchers built up a database of over 12,000 people and correlated how similar mock burglars microbiome signatures are to people in our database. It's complicated, but they are getting really close to identifying somebody's lifestyle traits based on the microbial signature they leave behind at a crime scene.

Jack Gilbert, Director of the Microbiome Center and a Professor of Surgery at the University of Chicago, said, "We leverage genome sequencing, especially the Illumina platforms – DNA extraction, and PCR amplification, much the same way as we would with human DNA sequences. We identify a particular gene present in all bacteria which we then sequence and use to determine which bacterial organisms are present in different subjects and what makes an individual unique."

"We then produce a probability estimate that your bacteria would be found in a certain environment. Using advanced statistical techniques, we try and identify whether your bacteria’s sequencing data can place you at that crime scene."

The way in which they analyze the microbiota is by looking for unique strains of organisms. We all have one particular species of E. coli living inside our gut, and we all have Staphylococcus epidermidis living in our skin, but each individual has a strain with a genotype and genome unique to them. It evolves with you and mutates over time, and we call those mutations biomarkers.

"We're using that information to try and identify whether we can pull out particular genotypic mutations, or biomarkers, which are unique to an individual. We are trying to answer a very particular question; whether the microbiome profile of an individual is stable and stays with you throughout your life."

The researchers hypothesize based on all the data collected that have a unique strain based composition which is a fingerprint of microbiota, but they have not proved this, and there are lots of factors that could alter this theory. Part of this project is to try and identify whether our microbial fingerprint stable, and how stable it is.

"The future is really exciting. We can potentially use the microbiome in forensic science, but that would be in the distant future. The human DNA program for forensic evidence took decades, and we’re only just starting our journey. "

"What's most exciting is we can also use the microbiome information inside our bodies in personalized medicine, using the microbiome to predict whether an individual will respond to a particular therapy."

"We could screen a cancer patient’s microbiome and determine if they have the biomarkers that can indicate their response to immunotherapy, which can help healthcare professionals identify their ideal strategy for therapy. We can use this to tailor treatment to the individual rather than the average treatment of a population.