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After programming of the general compositional architecture of the gut microbiota in early life, the established microbial ecosystem remains fairly stable and resilient to perturbations throughout life. Such perturbations include infections, colonic cleansing, diet or antibiotic intake.  While this is stability and resilience is generally of great benefit for the host, it becomes a challenge when we try to modify an compromised microbiome by the intake of probiotics or fecal microbial transplantation.  Before we can move on to modulate a maladaptive or disease related gut microbial composition by such interventions, there is a need for basic insight into the factors that influence whether and under what circumstances new strains of bacteria can integrate into a pre-existing, complex microbiota.

This latest study from the Sonnenburg lab demonstrates in mice that the combined administration of a specific sugar molecule called porphyry and a microbial strain that is not part of the normal gut microbiota but which contains the genes for the exclusively utilization of this sugar molecule results in the engraftment of the new microbe into the existing gut microbial ecosystem. As stated by the authors: “Privileged nutrient access enables reliable engraftment of the exogenous strain at predictable abundances in mice harbouring diverse communities of gut microbes.

These findings have important implications for the development of future therapeutic strategies using the engraftment of lacking or novel microbial species into our gut microbiome.  Such strategies may become important of the treatment of such various disorders as autism spectrum disorders, inflammatory bowel disorders and obesity.