Species in the Genus Bifidobacterium

Bifidobacteria were first described at the beginning of 1900 by the French paediatrician Tissier (Tissier, 1900), who observed a low number of bacteria characterized by a peculiar Y-shaped morphology in stools of infants with gastrointestinal disturbances when compared with those from healthy infants. He suggested that these bacteria could be administered to patients with diarrhea to help to restore a healthy gut microbiota. At the same time Metchnikoff, a Russian zoologist, pioneer researcher on immunology, correlated the potential life-lengthening properties of lactic acid bacteria with the longevity of Bulgarian peasants consuming large amounts of yogurt (Metchnikoff, 1908). This intuition has been the basis of the current concept that bifidobacteria are often associated with health-promoting activities, either as an endogenous member of the gut microbiota (immunomodulation, antagonistic activity toward pathogens, etc.) or as allochthonous probiotics species (restoring healthy gut microbiota). The intestinal microbiota studies started to reveal the great influence of bifidobacteria, which are considered helpful not only in the gastrointestinal apparatus but also in other systems, such as nervous [e.g., depression (Savignac et al., 2015)] and bone [e.g., arthritis reumatoides (Zamani et al., 2016)] systems. The current extensive genomic analyses will allow a deeper understanding of bifidobacterial diversity and will reveal host–bifidobacterial interactions in a more precise manner that could help in maintaining human and animal health. At the basis of all these studies, there is the knowledge of bifidobacterial species features and occurrence and the discovery of new species, obtaining new isolates that could be investigated for beneficial propertie