Paul Tullis in Nature:
Apart from the treadmill desk, Pieter Dorrestein's office at the University of California, San Diego (UCSD), is unremarkable: there is a circular table with chairs around it, bookshelves lined with journals, papers and books, and a couple of plaques honouring him and his work. But Dorrestein likes to offer visitors a closer look. On his computer screen, he pulls up a 3D rendering of the space. Four figures seated around the table — one of whom is Dorrestein — look as if they've been splashed with brightly coloured paint. To produce the image, researchers swabbed every surface in the room, including the people, several hundred times, then analysed the swabs with mass spectrometry to identify the chemicals present. The picture reveals a lot about the space, and the people in it. Two of Dorrestein's co-workers are heavy coffee drinkers: caffeine is splotched across their hands and faces (as well as on a sizeable spot on the floor — a remnant of an old spill). Dorrestein does not drink coffee, but has left traces of himself everywhere, from personal-care products to a common sweetener that he wasn't even aware he'd consumed. He was also surprised to find the insect repellent DEET on many of the surfaces that he had touched; he hadn't used the chemical in at least six months.
Then there were signatures of the office's other inhabitants: the microbes that reside on human skin. Dorrestein has been using mass spectrometry to look at the small molecules, or metabolites, produced by these microbes, and to get a clearer picture of how microorganisms form communities and interact — with other microbes, with their human hosts and with the environments that they all inhabit. He has analysed microbial communities from plants, seawater, remote tribes, diseased human lungs and more, in an effort to listen in on their chemical conversations: how they tell one another of good or bad places to colonize, or fight over territory. The work could identify previously unknown microbes and useful molecules that they make, such as antibiotics.