Gut-living bacteria, also known as the gut microbiome, have been shown to play an important role in host health by supporting the immune system, nutrition, development and even influencing behaviour. Understanding the gut microbiome of wild endangered animals and the role it plays in their health could have significant applications in species conservation and management. 

Nevertheless, little research has been done in this area and many of the ways in which the host’s environment and genetics shape the diversity of the gut microbiome remain unknown. Recently, researchers from the Central University of Kerala, Kasaragod, in collaboration with the Institute of Infectious Diseases, Switzerland, published the gut microbiome of the Indian Bison, locally known as ​“Gaur”. The researchers also investigated how domestication influences the gut microbiome, especially in the context of Indian wild animals. 

Gaurs are endemic to South and Southeast Asia and the majority of their populations live in India. They are considered a vulnerable species by IUCN. Gaurs are mainly restricted to national parks in the Western Ghats, central Indian highlands, and Northeastern Himalayas. The domesticated cousin of gaur is ​“Mithun”, which is believed to have diverged from wild gaur more than 8000 years ago. 

For this study, researchers collected faecal samples from both wild and captive gaurs as well as from mithuns. The faecal microbiome, which represents an amalgam of bacteria from different regions of the gut, was analysed by high-throughput sequencing of the 16S rRNA gene of the bacteria, a common approach for such purposes. Interestingly, this analysis revealed that domestication leads to a severe reduction in gut microbial diversity in both captive and domestic forms of gaur in comparison to their wild counterparts.

The study found that two beneficial bacterial families, Ruminococcaceae and Lachnospiraceae, which play vital roles in digestion in herbivores, showed lower abundance in captive and domestic populations. Both bacterial families are also important members of the human microbiome. The bacterial composition also suggested that captive and domestic gaur had impaired metabolism and immune function compared to wild gaur. According to Wasimuddin, a scientist from Institute of Infectious Diseases, Switzerland and one of the authors of the study, ​“Such anomalies in captive gaur and domesticated mithun could have important health and conservation implications for both captive and free-ranging gaur individuals.” 

A significant number of wild animals live in zoos in India and issues related to their health and well-being are primary concerns for zoo management. Many such issues are related to the animal’s natural diet, which can influence the gut microbiome. For example, chronic gastritis is a common cause of cheetah death in captivity for which an altered diet has been suggested to be one of the major factors. Studying the gut microbiome can thus help in identifying diet-related health issues in animals living in zoos. 

“Future studies should focus on species that are in conservation breeding programs. This allows the collection of samples and close monitoring of individuals. My expectation is that herbivores, in particular, would have important effects prompted by the change in the gut microbiome. So it is exciting times, but the real growth will be made when some controlled experiments are done,” says Karthikeyan Vasudevan, a senior principal scientist in Laboratory for the Conservation of Endangered Species (LaCONES) at Centre for Cellular and Molecular Biology, Hyderabad, who was not associated with the study.

Other than domestication, gut living bacterial communities of wild animals can be drastically changed by issues such as animal diseases, habitat fragmentation, hybridization and interaction with domestic animals, or by other anthropogenic activities, and can have an adverse effect on wild animal health. ​“Very little is known about gut microbiomes of wild animals especially in India. Such studies can shed light on host-microbiome evolution in nature in a broader sense but also increase our understanding of healthy host microbiomes and host ecology, a piece of essential knowledge for species conservation in the current Indian scenario,” says Wasimuddin.