First overview of archaea in vertebrates

Uncovering how host relatedness influences the diversity of archaea in the vertebrate gut

Archaea are often mistaken as bacteria, given that both are small, single-cell organisms. However, archaea are as genetically different from bacteria as humans are from bacteria. While archaea are found in most environments, including the human gut microbiome, relatively little is known about them. An international team of researchers from Germany and Austria, led by Nicholas Youngblut at the Max Planck Institute for Developmental Biology in Tübingen, Germany, has compiled the first large scale assessment of archaeal diversity in the vertebrate gut. The study shows that the diversity of archaea in the vertebrate gut is greater than previously thought. Moreover, the study shows how the relatedness of animals and their diets affects archaeal diversity.

Archaea are the third domain of life, separate from the domains of bacteria and eukaryotes. While bacteria and archaea are both unicellular organisms that lack a nucleus, they are very different in key ways. For instance, archaea uniquely generate methane by consuming the waste products of bacterial fermentation. Unlike bacteria, no pathogenic species of archaea have been discovered, which is a major reason why more attention is paid to bacteria in the animal microbiome. As a result, little is known about the diversity of archaea in the vertebrate gut and what factors influence this diversity.

Like a biological fingerprint, specific groups of microbes colonize the guts of birds, mammals, amphibians, reptiles and fish. In a new paper, researchers revealed how archaea fit into this picture. "We were amazed by the specificity but also diversity of the archaeal species we found in the gut of vertebrates. Among them was the archaeon Methanothermobacter," explained Nicholas Youngblut of the Max Planck Institute for Developmental Biology, who is lead author of the study. "Methanothermobacter is known to occur only in hot environments of about 60 degrees Celsius, so its detection in a large number of different vertebrates was surprising. We saw the archaeal genus particularly common and widespread among birds, which may be due to their higher body temperature of about 40 degrees Celsius or warmer."

A dataset of impressive size and quality