What do we have in common with blackbirds, frogs, and rabbits? We all have guts that are brimming with bacteria. However, while we know a great deal about human gut bacteria, the relationship between intestinal microbes and the health and lifestyle of wild animals is relatively unclear. Indeed, these tiny gut-dwellers could be the secret behind why some animals eat foods like rotting meat or poisonous plants without getting sick, or are immune to various diseases. 

In a new study published in Science, scientists sought to learn more about the gut microbes in animals from diverse classes, such as mammals or birds, and exhibiting different feeding behaviors, geographical location, and traits like body mass and lifespan. 

The investigators collected poop from 180 species of animals across the world, including everything from penguins and gorillas to kangaroos and turkey vultures. After sequencing DNA in the poop, the investigators used computer programming to characterize the bacterial community within the samples. 

They found that the animals’ gut bacterial communities varied depending on their class and traits like diet, body mass, and social structure (i.e. solitary vs social). Excitingly, over 900 of the 1209 bacterial species identified had never been recognized before. These mysterious microbes likely confer health benefits to their host. For instance, the investigators discovered novel microbe-associated enzymes in the gut of griffon vultures, which eat dead or decaying animals, that can degrade bacterial toxins. These enzymes may protect the birds from getting sick when they chow down on pathogen-infested meat. Similarly, some animals had microbial genes in their guts presumably associated with antibiotic biosynthesis or degradation of human-made chemicals. 

These results shine light on the associations between gut bacteria and animal physiology and behavior. Moreover, they suggest that animal guts may be gold mines for discovering bacteria with potential clinical and industrial applications, including those that produce novel antibiotics or compounds capable of eliminating industrial waste.