Love Dalén, Peter Mortensen / University of Stockholm
Remains of a mammoth tooth
Genetic sequencing techniques revealed the DNA of 310 microbial species associated with an older host ever registered: in teeth samples and bones of leaf mammoths and-temple mammutes.
The analysis of bones and teeth of prehistoric mammoths (Mammuthus) allowed to identify some of the microorganisms that have inhabited the mouth and body of these animals one million years.
O, published on Tuesday in Cell magazine, describes the oldest microbial DNA ever sequenced, and shows that certain species of pathogenic bacteria today associated with the death of African elephants (African loxodonta), they had already infected their distant cousins.
Conclusions offer “a good opportunity to get a global view of what kind of bacteria or viruses we could find in this extinct species,” he told The Paleomicrobiologist Benjamin GuinetInvestigator of the Center for Palaeogenectics, in Stockholm, first author of the study.
Future research can help you realize how microorganisms have contributed to the adaptation of these animals to various environments and if played some role in their extinction.
Pathogenic microbes
So far, investigation in old remains has focused mainly on human DNA and man-associated microorganisms, being rare studies on microbes and hosts in prehistoric animals.
To explore the relationship between mammoths and microorganisms, the team analyzed ancient Microbial DNA extracted from teeth, skulls and skin from 483 specimens.
Fossils cover several geographical locations -from North America and Britain to Siberia-and date from the beginning of the Pleistocenic, about a million years ago, until the extinction of the last mammoths of Wrangel Island (out of Siberia), already in the Holocene, about 4,000 years ago.
The investigators identified 310 microbial species associated with mammoth tissues. Many belonged to the environment and will have colonized the remains after the death of the animals, so the team filtered this DNA “post mortem”Concentrating on the bacteria that inhabited the mammoths in life.
Using metagenomic screeningsequencing technique that allows you to analyze genetic material in samples composed of genomes of multiple organisms, scientists studied DNA present in fossils.
Then through phylogenetic inferencethey compared these sequences with those of modern bacteria to identify microbial genres.
The analysis revealed Six groups of microorganisms associated with the host, some of which will have caused disease in mammakes.
Among them was a strain near Actinobacilluspreviously isolated in pigs (Pig domesticus) and which may have integrated the oral mammoth microbiome.
The genre was also identified Pasteurellaclosely related to a pathogen linked to the death of dozens of African elephants In Botswana and Zimbabué in 2020. In this case, the bacteria infected the mouth of the animals before entering the bloodstream and causing fatal septicemia.
The team also rebuilt genomes from a bacterial family called Erysipelothrixfrom samples of four leaf mammoths and a 1.1 million-year-olds-the Microbial DNA associated with the oldest host in which it is recorded.
Unlike the other bacterial groups, present only in dental cells, this microorganism It was also detected in bone tissue.
Ancient microbiomas
The concrete effects of these bacterial colonies on mammoth health are difficult to determine only on this genetic analysis. Still, researchers stress that work offers a first view of microbes that inhabited prehistoric animals.
Eva-Maria Geiglpaleogeneticist at the Institut Jacques Monod, in Paris, questions the biological relevance of analysis of samples over a million years, given the lack of appropriate references for comparison. But he recognizes that the team “certainly did a good job and produced a large amount of data.”
“The article shows a good proof of concept: Even some very old bacteria can be genetically recovered, ”he adds.
These findings provide a basis for future investigations into old microbiomas and their impact on health and disease, the authors conclude. “It is very interesting to be able to tell this story. We want to open the book of life and widen the boundaries of what we can know, ”summarizes Guinet.
