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.

Purpose: To explore the laxative effect of Lacticaseibacillus rhamnosus Glory LG12 from the perspective of the stem cell factor (SCF)/C-kit signaling pathway. Methods: Male ICR mice were randomly divided into five groups: control, model, low- (1.5 × 10⁶ CFU/mouse), medium- (1.5 × 10⁷ CFU/mouse), and high- (1.5 × 10⁸ CFU/mouse) dose L. rhamnosus Glory LG12. After 15 continuous days of gavage, all mice were further gavaged with loperamide hydrochloride suspension (4 mg/kg) to establish a mouse model of constipation. Body mass, the time taken until the first black stool excretion, the number and mass of black stool within 5 hours, small intestinal transit rate, serum levels of gastrointestinal regulatory peptides and inflammatory cytokines, colonic SCF and C-kit transcription levels were measured, and colonic pathology was examined. Results: Compared with the model group, medium- and high-dose L. rhamnosus Glory LG12 significantly reduced the time taken until the first black stool excretion (P < 0.001), increased the number and mass of black stools within 5 h (P < 0.01 and P < 0.001, respectively), and improved the ink propulsion rate in the small intestine (P < 0.001). In addition, both treatments elevated the serum levels of motilin (MTL), gastrin (Gas), substance P (SP), and interleukin 10 (IL-10), reduced the levels of endothelin-1 (ET-1), somatostatin (SS), vasoactive intestinal peptide (VIP), and IL-6, upregulated the relative mRNA expression of SCF and C-kit in colonic tissue was (P < 0.01, P < 0.001), and restored damaged colonic barrier. Conclusion: L. rhamnosus Glory LG12 promotes gastrointestinal motility by affecting the release of gastrointestinal regulatory peptides and inflammatory cytokines through the modulation of the SCF/C-kit signaling pathway, thereby alleviating constipation symptoms.

This study was conducted in order to investigate the effect of Lactobacillus helveticus LH43, which has the ability to produce high-molecular-mass extracellular polysaccharides, as an auxiliary starter on the gel properties and protein conformation as determined using a texture analyzer, a rheometer, scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), fluorescence spectrophotometry and circular dichroism (CD) spectroscopy. The results showed that the application of L. helveticus LH43 as an auxiliary starter significantly enhanced the textural properties, water-holding capacity (WHC) and rheological characteristics of yoghurt and improved its microstructure and flavor characteristics. Additionally, the strain reduced the surface hydrophobicity, free sulfhydryl content and relative content of random coil of yoghurt proteins, and increased the relative content of α-helical structures, confirming α-helix and random coil to be intrinsic factors leading to differences in the gel properties of fermented milk. In conclusion, L. helveticus LH43 can be used to improve the gel properties of dairy products, and this study provides a new reference for improving the fermentation process of yoghurt.

Breast milk is the safest and most perfect natural food for infant growth and development. As one of the most important components in breast milk, the milk fat globule membrane (MFGM) is a 3-layer membrane structure surrounding milk fat globules (MFG). This unique structure not only maintains the stability of milk but also plays an important role in the digestive and metabolic processes of infants. In this article, we introduce the reader to the composition and structural specificity of MFGM, review the sequential digestion of MFGM depending on several enzymes in the mouth, stomach and intestine of healthy infants, and elaborate on the interaction mechanism between MFGM and various enzymes, in order to provide a reference for relevant studies.

2’-Fucosyllactose (2’-FL) shows the potential to support intestinal health as a natural prebiotic that bridges the gap between infant formula feeding and breastfeeding. However, the effect and mechanism of 2’-FL in improving intestinal permeability are not clear. In this study, we constructed human microbiota-associated (HMA) mouse models by colonizing healthy infant feces in mice with antibiotic-depleted intestinal microbiota. The protective effect of 2’-FL on the intestinal permeability was explored using the HMA mouse models, and the combination of metagenomics was used to analyze the possible mechanisms by which the microorganisms reduced the intestinal permeability. The results showed that 2’-FL decreased the concentration of markers of intestinal permeability (enterotoxin and diamine oxidase (DAO)) and increased the expression levels of tight junctions (occludin and claudin). Metagenomics revealed the enrichment of Bifidobacterium and increased the expression of glycoside hydrolases (GHs), including GH31, GH28, and GH5. In conclusion, 2’-FL strengthened intestinal permeability function by improving microbiota composition to control the translocation of harmful substance.

Infant formula (IF) based on cow milk and goat milk is a substitute food for infants who are underfed with human milk. In our previous study, we reported the composition and physicochemical stability of IF based on milk from cows and goats and a combination of both milks. Here, we investigated the effects of these 3 IFs on intestinal immunity and short-chain fatty acid production (SCFAs) using human microbiota-associated (HMA) mice and selected human milk as a positive control. The results showed that goat milk-based IF is associated with a functional immune advantage, due to the rise in the levels of immune-related cytokines interleukin (IL)-2 and IL-10, decreased levels of intestinal permeability markers D-lactic acid and endotoxin, and increased mRNA levels of intestinal tight junction proteins occludin and claudin. In addition, the intestine of mice fed with goat milk -based IF contained 12.06 μmol/g acetate, 2.42 μmol/g propionate, and 1.72 μmol/g butyrate, which reached 69%, 79 %, and 60% of the levels in human milk, respectively. Our results indicate that goat milk-based IF improves intestinal immune function and promotes the production of intestinal SCFAs.