The effects of exposure to radionuclide contamination on microbiota of wild mammals

All animals host diverse communities of bacteria within their digestive system, so-called ‘gut microbiome’. The gut microbiome help animals to digest food, and protect them against pathogens and toxic compounds. As changes in the gut microbiome can impact host health, it is important to understand processes that influence diversity and composition of these microbial communities. Although quite a lot is known about how diet and lifestyle can alter the types of gut bacteria in humans and laboratory animals, relatively little is known about the factors that can affect the gut bacteria of wild animals, especially influence of human activities. The studies in Anton Lavrinienko’s dissertation showed that wild animals living in areas contaminated by radioactive material (radionuclides) have an altered gut microbiome composition compared with animals that do not live in areas affected by an increase in radiation.

In his studies, Anton Lavrinienko collected faecal samples from small rodents living in areas surrounding the Chernobyl (Ukraine) and Fukushima (Japan) nuclear accident sites. These samples were used to obtain millions of sequences of DNA to identify and count the types of bacteria living within the guts of captured animals. Such gut microbiota profiling resulted in a catalogue of hundreds of different bacterial taxa. Interestingly, the abundance of several key gut bacteria was altered in animals exposed to radioactive material as compared to animals caught from the uncontaminated with radionuclides control areas. Furthermore, field studies conducted by Lavrinienko in Ukraine and Japan show comparable influence of radiation exposure on the gut microbiota of multiple species of rodents and demonstrate that such changes in gut microbiome of exposed animals can be persistent over time.

Overall, the studies in Anton Lavrinienko’s dissertation show that exposure to environmental contaminants has clear potential to affect microbiota associated with wild animals. This research raises several questions, among which the most important is whether the altered microbiome is an indicator of poor wildlife health or such changes are adaptive and improve health of animals living in a radioactive environment. Understanding the causes of microbiota variation, and its eventual consequences (positive or negative) for animal health is critical in a rapidly changing world, where human disturbances are commonplace.

This work was supported by the Academy of Finland, the Oskar Öflund Stiftelse, Scholarship Fund of the University of Oulu, and by the University of Oulu Graduate School.