A groundbreaking study has shed new light on the microbiomes of mammoths by examining hundreds of remains, including those of a steppe mammoth found near the Adycha River in northeastern Russia. This study, led by Benjamin Guinet from the Swedish Museum of Natural History, has analyzed microbial DNA from no fewer than 483 remains spanning over one million years. These remains were uncovered from seven sites located in Canada and Russia.
Using a variety of genetic techniques, Guinet and his team identified 310 microbes from different mammoth tissues, ranging from teeth to tibia. While most of these microbes are thought to have been derived from the surrounding environment after death, six have been identified as ‘host-associated’, meaning they lived symbiotically inside or on their hosts. The dataset assembled by Guinet and his team includes 440 newly sequenced and unpublished samples from a 1.1-million-year-old steppe mammoth found near the Adycha River in northeastern Russia.
In 2021, scientists successfully recovered DNA from a molar of this particular mammoth, making it the oldest DNA ever sequenced from animal remains. This mammoth, known as the ‘Adycha Mammoth,’ is particularly famous. From this same molar, the team recovered genomic evidence of a host-associated microbe known as Erysipelothrix, marking the oldest discovery of its kind.
Ancient microbes found in mammoth remains
Erysipelothrix is a type of bacteria that has previously been isolated from dogs, pigs, cattle, and humans, and is thought to be involved in endocarditis—a potentially fatal infection of the inner lining of the heart. Evidence of Erysipelothrix-like bacteria was also discovered in woolly mammoth bones from different time periods and locations, suggesting a long-term association with mammoths that may have influenced their evolution.
The study also found genomic evidence of five more types of host-associated bacteria, including Pasteurella and Streptococcus. Some Pasteurella DNA isolated from two Late Pleistocene mammoth samples was very similar to a strain of bacteria identified as causing fatal septicaemia in six African elephants in Zimbabwe in 2020. Additionally, two distinct types of Streptococcus identified from six woolly mammoth teeth were found to be distantly related to a strain responsible for tooth decay in humans.
This study shows that bacteria isn’t inherently harmful. In fact, many of the types identified in this study, including Erysipelothrix, Pasteurella, and Streptococcus, can be harmless or even beneficial, only causing disease under certain conditions. For example, Pasteurella is involved in the production of succinic acid, a naturally occurring acid crucial for metabolism and energy production.
Not only has this latest study assembled a comprehensive database that will form the basis of further studies into the microbiomes of mammoths, but it has also demonstrated the possibility of detecting host-associated bacteria in the remains of extinct animals. This new research area has the potential to change our understanding of the long-term health of extinct animals and how their microbiomes may have shaped their evolutionary trajectories.
