Human milk oligosaccharides (HMO) have complex structures and selectively stimulate the growth of probiotic bifidobacteria in the intestine of breast-fed infants. Infant gut-associated bifidobacteria provide molecular tools to metabolize HMO with strain specificity, such as glycosyl hydrolases. This review summarizes the structure of HMO and the mechanism underlying HMO metabolism by infant gut-associated bifidobacteria. The focus of this review is on the current advances in the intraspecific differences in bifidobacterial HMO metabolism and the tools involved in the metabolic process.

Exopolysaccharides (EPS) produced by lactic acid bacteria (LAB), with a variety of physiological functions, play a significant role in the improvement of physical properties of fermented dairy products. The structures and functions of EPS synthesized by different LAB strains are highly diverse. Therefore, this review summarizes the progress that has been made in recent years in studying the structure of EPS from LAB and its effect on physical properties and health-beneficial functions of fermented dairy products, in order to lay a theoretical foundation for developing new fermented dairy products with stable quality and desired health-beneficial functions.