Study of ancient British oral microbiomes reveals shift following Black Death

“This study places unnecessary responsibility and liability on Indigenous communities to participate in microbiome research whose benefits may not directly benefit Indigenous peoples,” Weyrich said.

A more accurate and responsible approach, Weyrich said, would be to directly examine the oral cavity preserved in calcified dental plaque, called dental calculus, from the ancestors of industrialized populations, with the permission and cooperation of later generations of the population and stakeholders. Microbiome. In the largest study of ancient dental calculus to date, Weyrich and her colleagues collected dental material from 235 individuals buried from approximately 2,200 BC to AD 1853 at 27 archaeological sites in England and Scotland. in the ruins.

Researchers process samples in ultra-sterile ancient DNA laboratories to minimize contamination. They identified 954 microorganisms and determined that they belonged to two distinct bacterial communities, one dominated by the genus Streptococcus, which is common in the oral microbiome of modern industrialized populations, and another dominated by the genus Methanobrevibacter, which is currently present in the oral microbiome of modern industrialized populations. Bacteria are largely thought to have wiped out healthy industrialized populations.

In exploring the origins of these two communities, the team found that nearly 11% of the total variation in microbiome species composition could be explained by temporal changes, including the arrival of the second plague pandemic. But how did the second plague pandemic lead to changes in the oral microbiome?

“We know that survivors of the second plague pandemic had higher incomes and were able to afford higher-calorie foods,” Weirich said. “The pandemic may have triggered changes in people's diets, which in turn affected the composition of their oral microbiomes.”

The research team used a new method to investigate whether changes in diet affect the emergence of Streptococcus species and the extinction of Methanobrevibacter species. They listed possible diet-related functional differences between the two groups of bacteria. For example, functions related to high or low dietary fiber digestion, carbohydrate metabolism, and lactose (a sugar in milk) metabolism.

The researchers found that Streptococcus-dominated bacteria had additional functional traits that were significantly associated with low-fiber, high-carbohydrate diets, as well as dairy consumption—all features of modern diets. In contrast, the group dominated by Methanobrevibacterium lacked traits associated with dairy and sugar consumption that characterize the diets of some ancient humans.

The research team further determined that Streptococcus bacteria are associated with the presence of periodontal disease, which is characterized by infection and inflammation of the gums and bone surrounding the teeth. When the disease progresses, bacteria can enter the bloodstream through the gum tissue and can cause respiratory disease, rheumatoid arthritis, coronary artery disease and blood sugar problems like diabetes. On the other hand, the Methanobrevibacterium group is associated with the presence of skeletal pathology.

Our study shows that the modern oral microbiome may reflect past dietary changes caused by the second plague pandemic,” Weirich said. “Importantly, this work contributes to our understanding of modern chronic noncommunicable diseases.”

Other Penn State authors on the paper include graduate student Abigail Gancz; Michelle Nixon, assistant research professor of information science and technology; Sterling Wright, graduate student; Emily R. Davenport, assistant professor of biology; Justin Seale Justin Silverman, assistant professor of information science and technology. Other co-authors include Andrew Farrer, a postgraduate student at the University of Adelaide; Luis Arriola, a postgraduate student at the University of Adelaide; C. Adler, a senior lecturer at the School of Dentistry, University of Sydney; Neville Gully, a postgraduate student at the Adelaide School of Dentistry, University of Adelaide; Deputy Dean of Teaching; Alan Cooper; Kate Britton, Professor of Archeology, University of Aberdeen; Keith Dobney, Dean of the School of Historical and Philosophical Inquiry, University of Sydney.

The research was supported by the Australian Research Council, the US National Science Foundation and Penn State University.

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