Ecological and functional implications of the acid-adaptation ability of Bifidobacterium: A way of selecting improved probiotic strains

Probiotics are live micro-organisms that exert health benefits on the host when ingested in appropriate numbers. Bifidobacterium strains are some of the most important probiotics used for human consumption. The high sensitivity of the strains of this genus to acidic conditions can, however, impair their survival in adverse environments such as the stomach and in fermented foods, and, therefore, limits their use as live probiotic cultures. The optimization of strategies based on stress adaptation and cross-protection mechanisms of bifidobacteria constitutes an attractive option to improve their technological performance and functionality. The ability of Bifidobacterium strains from different ecosystems to survive to acidic conditions as well as the success and limitations of the application of acid stress adaptation treatments to improve their stress tolerance and biological properties are reported. The potential use of these strategies to expand the spectra of probiotic strains and products currently marketed is discussed.