show Abstracthide AbstractGnotobiotic mice colonized with known bacterial communities are extensively used as models to study the role of the gut microbiota and its association with diseases. We developed a defined consortium of 12 cultivable murine isolates, named the Oligo-Mouse Microbiota (Oligo-MM), which represent the main bacterial phyla colonizing the mouse and human intestine. Such a defined bacterial collection represents an ideal model for analyzing genome evolution of bacteria in their natural host, and for predicting their functionome and metabolic capacity, both as whole community and as single species.