Usage of Cultured Human Fecal Microbiota for Colonization of Caenorhabditis elegans to Study Host–Microbe Interaction

The role of the microbiota in health and disease is a research area receiving much attention in academia and industry. A person’s microbiota refers to a community of microorganisms found mainly in the gut. It is estimated that around 39 trillion bacteria can be found on and inside the human body and there is increasing evidence that they influence human health. Advances in sequencing techniques are revolutionizing characterization of the human microbiome. However, causality and underlying molecular mechanisms are still largely unknown due to the complexity of the human microbiome and its interaction with the host. Turning towards simpler host organisms and using well-defined microbiomes are two ways to strengthen studies of causality and mechanism. Here, we show that the nematode Caenorhabditis elegans can be used as host to study sub-microbiomes derived from human feces samples prepared for fecal microbiota transplantation following a simple feeding protocol. Approximately 200 amplicon sequence variants were identified in the worm gut following transplantation with human fecal microbiota samples. We find that the gut microbiome does not simply reflect the bacterial community initially fed to the worms. Hence, our experimental setup can be used to identify and characterize host genetic factors shaping the microbiota and improving our understanding of host–human microbiome interactions.