It’s an exciting time for ecologists who study microbes. DNA sequencing has grown so cheap and fast that they can run around identifying bacteria living just about anywhere they can reach with a cotton swab. Turns out, bacteria are everywhere, even in the cleanest houses, and scientists are starting to wonder: do those bacteria in the home reflect the bacteria that live inside the inhabitants?
And if so, can they travel from person to person?
A small insight into this question came at one of the presentations at the International Human Microbiome Congress (covered by New Scientist in a short piece here). James Scott, who studies molecular genetics at the University of Toronto, reported that the gut microbes of babies, as found in their poop, were also in the dust in the babies’ homes. It’s not clear whether this means that bacteria in the dust are colonizing the babies or vice versa—or both—but it’s still something of a surprise. Gut microbes don’t seem like the sort to thrive outside the body, as they tend to require an oxygen-free environment. But maybe the gut bacteria in the dust are in a dormant form, waiting to be absorbed into a new gut before flowering into life again.
The corollary of this finding is that perhaps the other inhabitants of that home might pick up those microbes. Your gut microbiome, thus, would be closer to your roommates’ than to a stranger’s, something that would be easy to test with modern sequencing techniques. There’s also room to speculate that as we learn more about the microbiome’s relationship to disease, the swapping of microbes within a household could reveal an infectious component to illnesses that we don’t currently think of that way. It’s just a speculation now, but an interesting one.
The scientists’ blood-sucking accomplices
What’s the News: Scientists searching for new and endangered species in tropical highlands face a Catch 22. Spotting shy creatures is the order of the day, but bushwhacking through forests is anything but subtle. How can you get a sense of what’s there when you can’t get close enough to see it?
Environmental DNA analysis is one of the answers—checking out the DNA in soil, for instance, can reveal what pooped there recently in amazing detail. But for a technique that can reach beyond a given patch of ground, scientists have been investigating using leeches from streamwater as their source of DNA. It turns out that blood from their last meal sticks around in their gut for a good long time, and they happen to be partial to human blood too—which makes them, in the scientists’ words, “easy to collect.” A new paper gives proof that the technique is valuable: blood in leeches collected from a Vietnamese rainforest reveals the presence of six mammalian species, some of them rare.