A strain of Bifidobacterium longum biovar infantis deposited in the Colección Española de Cultivos Tipo (CECT) under the accession number CECT 7210, or a mutant or variant thereof having an activity of inhibiting rotavirus and having the ability to produce a peptide from the fermentation of a substrate, said peptide having a length from 11 to 17 amino acids and an amino acid sequence which comprises SEQ ID NO: 1 or a derivative of said peptide. The invention relates to the use of these bacteria as probiotics.
