Strain libraries are like seed banks, cryobanks or microbiological laboratories that collect, store and catalogue different strains of bacteria as they are discovered and genotyped. Among the best-known strain libraries are the American Type Culture Collection Center (ATCC) or the Collection Nationale de Cultures de Microorganismes (CNCM) at the Institut Pasteur.
Example: Bifidobacterium breve B3 ATCC-SD5206, where Bifidobacterium indicates the genus, breve the species, B3 the strain and ATCC-SD5206 indicates that the strain is deposited at the American Type Culture Collection Center under code SD5206.