The genera Bifidobacterium, Parascardovia and Scardovia

Bifidobacteria, dominant or relevant inhabitants of the gut of man and animals, have been shown to provide health-promoting benefits to the host, but their mechanistic actions remain unknown. A decrease in gut bifidobacterial population has been linked to pathologies such as Crohn's disease, obesity, diabetes, allergy and nervous disturbances. Given the notable differences in the distribution of bifidobacteria between healthy subjects and those suffering disease, many studies have investigated Bifidobacterium characteristics and the factors influencing their modulation, nowadays the focus of ongoing research. This chapter describes the milestones in taxonomy and phylogeny, present-day methodologies for the characterization, identification and quantification of bifidobacteria, and their ecology and application. Finally, a list of the 35 Bifidobacterium species described to date is given, followed by a description of the closely “related” new genera, Scardovia and Parascardovia.