Association between bone marrow donor origin and gut microbiota composition following fecal microbiota transplantation in mice.

Fecal microbiota transplantation (FMT) has been reported as a method to directly alter the recipient's gut microbiota in order to normalize its composition and confer therapeutic benefits. It is essential to maintain a consistent gut microbiota in FMT donors. However, various environmental factors influence the maintenance of gut microbiota composition. We investigated whether bone marrow transplantation (BMT) donor origin, presumably affecting the resultant recipient immune environment, may influence FMT outcomes by conducting a study combining BMT and FMT treatments in mice. Our results show that the origin of the bone marrow donor affected the extent to which the FMT recipient microbiota resembled that of the FMT donor. However, these changes did not reduce the overall microbiota dissimilarity compared to FMT alone. Among the affected microbes, the relative abundance of a mucus-associated bacterium in the family Muribaculaceae was higher, suggesting sensitivity to the combined influence of BMT and FMT donor origins. These findings are consistent with the possibility that bacterial proximity to the intestinal epithelium could modulate persistence patterns in response to distinct post-BMT environments. Altogether, the observed trends suggest that differences associated with bone marrow donor origin may shape post-FMT microbial retention.