Human DNA shed into the air is collected and sequenced

Mammalian DNA can be collected from the air and sequenced with species-level resolution, a study has shown for first time.

Environmental DNA (eDNA) is DNA collected from environmental media including soil and water. Aquatic eDNA has been used successfully to detect the presence of aquatic animals such as crested newts. Researchers at Queen Mary University of London have now been able to detect mammalian DNA captured from the air in a laboratory.

Dr Elizabeth Clare, first author of the study published in PeerJ, said: 'Here we provide the first published evidence to show that animal eDNA can be collected from air, opening up further opportunities for investigating animal communities in hard-to-reach environments such as caves and burrows.'

The scientists used a pump to draw air from the chambers of naked mole rats, and the room in which they were kept, through micro filters with the aim of capturing shed skin cells and free-floating fragments of DNA.

DNA sequencing was then used to see if it was possible to distinguish the species present in the sample space. The researchers were able to detect naked mole rat and human DNA. Initially the team thought that the presence of human material was the result of contamination, but later realised that it was a reflection of the activity of researchers and those caring for the animals in the facility.

Although the presence of human DNA in study spaces may present a challenge when sampling natural environments for ecological research, the team noted that this effect could open up the research to avenues not initially considered. The team wrote in their paper: 'While not our target, most air samples contained human DNA, suggesting forensic applications', proposing that the technique could offer a novel detection method for crime scene investigations.

The team made the observation that their work could be used to advance the understanding of airborne diseases, particularly with reference to SARS-CoV-2, the virus which leads to COVID-19. Dr Clare said: 'At the moment social distancing guidelines are based on physics and estimates of how far away virus particles can move, but with this technique we could actually sample the air and collect real-world evidence to support such guidelines.'

The team originally hoped that their technology can be used to provide an effective and non-invasive way of monitoring wild animal populations in conservation efforts. Yet, the technology also has potential applications in forensics, anthropology and even medicine.