Breast milk isn't sterile, but contains as many as 600 different species of various bacteria, including beneficial Bifidobacterium breve, B. adolescentis, B. longum, B. bifidum, and B. dentium.
Среди них бифидобактерии нескольких видов (B. breve, B. adolescentis, B. longum, B. bifidum, B. dentium).