There are abundant microbial communities in the human intestine, some of which have begun to colonize in it even before birth. The period from gestation to 2 years old is the window of opportunity for the development of the intestinal microbiota. During this period, its composition is susceptible to a variety of factors such as gestational age, delivery mode, feeding pattern, antibiotics, probiotics and prebiotics, environmental factors and host genes. The intestinal microbiota is crucial to infant development throughout its life and closely related to the health of infants. This review discusses the periods of colonization and change of the intestinal microbiota in early life and the factors affecting it, highlights the importance of the intestinal microbiota to infant growth and development, and puts forward the necessity of developing new foods.

The primary criterion for selecting probiotics having application potential is their adhesion capability to the host intestinal mucosa. The adhesion mechanism of probiotics is affected by many factors such as adhesins. Probiotics with high adhesion capability has a long intestinal residence time, contributing to their intestinal colonization in animals and stimulating intestinal barrier and metabolic functions, in turn maintaining the health of organisms. In addition, they can exert antagonistic effects against pathogens to protect intestinal health via many mechanisms such as producing antimicrobials and decreasing the adhesion capacity of pathogens and competitive binding sites. In this article, the adhesion mechanism of probiotics is reviewed, and a comprehensive overview of the state of the art in research on the adhesion characteristics and antagonistic activity against pathogens of probiotics is given.