ABSTRACTFecal microbiota transplantation (FMT) is used routinely to treat recurrentClostridioides difficileinfection (rCDI) and investigated as a treatment for numerous conditions associated with gut microbiota alterations. Metagenomic analyses have indicated that recipient colonization by donor bacteria may be associated with favorable clinical outcomes. Bifidobacteria are abundant gut commensals associated with health. We have previously demonstrated thatBifidobacteriumstrains transferred in FMT can colonize recipients in long term, at least for a year, and recovered such strains by cultivation. This study addressedin vitroadhesion and pilus gene expression of long-term colonizingBifidobacteriumstrains from FMT donors as well asin vivocolonization and capability to ameliorate antibiotic-induced microbiota disturbance. RNA-Seq differential gene expression analysis showed that the strongly adherentB. longumstrains DY_pv11 and DX_pv23 expressed tight adherence and sortase-dependent pilus genes, respectively. TwoB. longumstrains, adherent DX_pv23 and poorly adhering DX_pv18, were selected to addressin vivocolonization and efficacy to restore antibiotic-disturbed microbiota in C57BL/6 murine model. DX_pv23 colonized mice transiently with a rate comparable to that of theB. animalisBB-12 used as a reference. Although long-term colonization was not observed with any of the three strains, 16S rRNA gene profiling revealed that oral administration of DX_pv23 enhanced the recovery of antibiotic-disturbed microbiota to the original configuration significantly better than the other strains. The findings suggest that selected strains from FMT donors, such as DX_pv23 in this study, may have therapeutic potential byin vitroexpression of colonization factors and boosting endogenous gut microbiota.