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A person's home is their castle and they populate it with their own subjects - millions and millions of bacteria.

Scientists have found that when we move from one house to another – or even spend time in a hotel - we take all of our bacteria with us, and 'colonise' the space around us within a matter of hours.

These 'bacterial signatures' are unique and could be used to uncover crimes in future, just as today's investigators rely on fingerprints. 

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Scientists have found that when we move from one house to another – or even spend time in a hotel - we take all our bacteria with us and colonise the space around us within a matter of hours (illustrated)

Scientists from the US Department of Energy's Argonne National Laboratory and the University of Chicago examined the complex interaction between humans and the microbes that live on and around us.

The Home Microbiome Project followed seven families - comprising 18 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.

Researchers at the lab analysed the DNA of the samples to characterise the different species of microbes in each sample, according to the study published in Science.

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 in the way it was covered in microbes.

Researchers at the laboratory analysed the DNA of the samples to characterise the different species of microbes in each sample. They found that people substantially affected the microbial communities in a house. A stock image of 'superbug' microbes is pictured

They found that couples and their young children shared most of their microbial community and that regular physical contact made a difference in how bacteria spread.

People's hands were the most likely to have similar microbes, while their noses showed the most individual variation.

Perhaps unsurprisingly, more plant and soil bacteria was found in houses containing dogs and cats.

The research suggests that when a person, and their microbes, leave a house, the microbial community shifts noticeably in a matter of days.

Jack Gilbert, a microbiologist at Argonne, said that the effects are more extreme in hotels.

'Everyone thinks hotels are icky, but when one young couple we studied moved into a hotel, it was microbiologically identical to their home within 24 hours,' he told The Washington Post. 

'No matter what you do to clean a hotel room. Your microbial signal has wiped out basically every trace of the previous resident within hours.'

Dr Gilbert said that microbiome studies could serve as a forensic tool. 

Dr Gilbert said that microbiome studies could serve as a forensic tool and could be more sophisticated than fingerprints (stock image). He said that scientists could look at bacterial colonies to identify the last person to come into contact with a person and when it happened, which could help in many criminal investigations

Given an unidentified sample from a floor in this study he said, 'we could easily predict which family it came from.'

Because a microbial community shifts in a matter of days when a person leaves a location, he added: 'You could theoretically predict whether a person has lived in this location, and how recently, with very good accuracy.'

Dr Gilbert believes this technique could be more sophisticated than fingerprints.

He said that scientists could look at bacterial colonies to identify the last person to come into contact with a person and when it happened.

An actual fingerprint is rarely left on a body, but a microbial fingerprint certainly is,' he added.