Bifidobacteria are common inhabitants of human gut and play a significant role in establishing a well-balanced intestinal microbiota. The strain Bifidobacterium longum CECT 7347 (ES1) has been demonstrated to ameliorate damage caused by gluten in celiac disease (CD), both In vitro and in a murine model. Studies suggest that administering this B. longum strain to supplement the gluten-free diet could provide an additional strategy, thereby improving the health status of patients. Here, we report an in-depth study of this strain, adopting a multidisciplinary strategy to demonstrate its safety according to FAO/WHO criteria for probiotic selection. Whole genome sequencing using a massive sequencing approach on the 454 platforms and annotation showed neither relevant virulence nor potential antibiotic resistance genes. It has been demonstrated that values of lactic acid isomer production, bile salt deconjugation and formation of biogenic amines, considered as specifi c traits to be evaluated according to FAO/ WHO, were very similar to levels previously reported in other Bifidobacteria. It has not shown acquired antibiotic resistance In vitro. Moreover, acute ingestion studies in immunocompetent and immunosuppressed BALB/c mouse models did not cause either mortality or morbidity in any group, and did not lead to signifi cant Bifi dobacterial organ translocation, even in the immunosuppressed group. Altogether, these results confi rm the safety status of the strain B. longum CECT 7347.
The safety of strain CECT 7347, together with its previously reported functional role in ameliorating gluten- related damage in CD, would indicate it is a probiotic strain.