Strange bacteria trapped in Neanderthal teeth could one day help researchers develop new antibiotics, according to a study published May 4 in the journal. Science (opens in a new tab)who used dental plaque from ancient and modern humans to investigate the evolution of oral microbes.
Each person has their own oral microbiome, a collection of hundreds of species of microscopic organisms that colonize our mouths. With hundreds of different species of microorganisms at any given time, the oral microbiome is large and diverse, varying depending on the environment in which a person lives.
To investigate the ancient human oral microbiome, christina warinner (opens in a new tab), a biomolecular archaeologist at Harvard University, invented new techniques to analyze prehistoric human dental plaque that has hardened into calculus, also called tartar. “The dental calculus is the only part of your body that routinely fossilizes while you’re still alive,” Warinner told Live Science. It also has the highest concentration of ancient DNA of any part of an ancient skeleton.
With just a few milligrams of dental calculus, Warinner can isolate billions of short snippets of DNA from hundreds of species, all jumbled together, and then put those snippets back together to identify known species. And studying ancient remains presents an additional hurdle: DNA found in dental calculus from humans of the past may come from microbes that have gone extinct.
In their new study, Warinner and his colleagues analyzed the dental calculus of 12 Neanderthals, one of our closest extinct human relatives; 34 archaeological humans; and 18 contemporary humans who lived from 100,000 years ago to the present in Europe and Africa. They sequenced more than 10 billion pieces of DNA and reassembled them into 459 bacterial genomes, approximately 75% of which were assigned to known oral bacteria.
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The researchers then zeroed in on two species of a genus of bacteria called chlorobium found in seven Superior Pleistocene-era (126,000 to 11,700 years ago) individuals in the study. Unknown species do not exactly match any known species, but are close to C.limicolafound in water sources associated with cave environments.
It’s likely that “these people who lived in these cave-associated environments got it in the drinking water,” Warinner said.
These chlorobium species were almost entirely absent from Tartar people who lived in the last 10,000 years. Between the Late Pleistocene and the Holocene (11,700 years ago to the present), over a span of about 100,000 years, humans have lived in caves, domesticated animals, and invented 21st-century plastics, all of which have their own bacterial colonies. different. Changes in chlorobium often seem to parallel the lifestyle changes of our ancestors.
Today, the microbiomes in people’s mouths are drastically different. “With intensive toothbrushing, oral bacteria are now kept at low levels,” Warinner said. “We take it for granted that we have radically altered the types of life with which we interact.”
john hawks (opens in a new tab)a University of Wisconsin paleoanthropologist who was not involved in the study told Live Science in an email that “one really interesting thing about microbes is that some of them weren’t known to us from our mouths at all; they came from the pond.” water tells us that these water sources were probably regular features of their lifestyles.”
The team also looked at so-called biosynthetic gene clusters (BGCs), or groups of genes needed to create a specific compound, to determine which enzymes chlorobium produced species. By isolating and understanding such BGCs, scientists could develop new drugs.
When inserted into live bacteria, the chlorobium The BGCs produced two new enzymes that may have played a role in photosynthesis. The new techniques could one day lead to new antibiotics, Warinner said.
“Bacteria are the source of virtually all of our antibiotics; we haven’t really discovered any major new classes of antibiotics in the last two years, and we’re running out,” Warinner said. “These methods give us the opportunity to search for potential antibiotic-producing SLBGs in the past.”