Genomics as a means to understand bacterial phylogeny and ecological adaptation: the case of bifidobacteria.

The field of microbiology has in recent years been transformed by the ever increasing number of publicly available whole-genome sequences. This sequence information has significantly enhanced our understanding of the physiology, genetics and evolutionary development of bacteria. Among the latter group of microorganisms, bifidobacteria represent important human commensals because of their perceived contribution to maintaining a balanced gastrointestinal tract microbiota. In recent years bifidobacteria have drawn much scientific attention because of their use as live bacteria in numerous food preparations with various health-related claims. For this reason, these bacteria constitute a growing area of interest with respect to genomics, molecular biology and genetics. Recent genome sequencing of a number of bifidobacterial species has allowed access to the complete genetic make-up of these bacteria. In this review we will discuss how genomic data has allowed us to understand bifidobacterial evolution, while also revealing genetic functions that explains their presence in the particular ecological environment of the gastrointestinal tract.