# Dynamic Alternations in Mother-Infant Dyad's Gut Microbiota over the Period of Six Months
## 5 Discussion  
As one of the highest densities of microecology on earth, intestinal microbiota is a community of key contributors to human nutrition. The gut microbiota is closely related to human health and nutrition. Since birth, the human microbiome plays a crucial role in influencing the health of the host. Understanding the changes in the human gut microbiome helps to construct the intestinal microecosystem. Metagenomic sequencing analyses have  
Figure 3: The clustering analysis of metabolic pathways of all samples. (**A**) Hierarchical Clustering Analysis of microbial metabolic pathways in faecal samples from mothers and infants. Hierarchical Clustering Analysis was performed based on R package cluster. *: P value was less than 0.05. (**B**) Cluster heatmap of differential metabolic pathways between the maternal and infant’s faecal microbiota. The 28 significant differential metabolic pathways were identified by _t_-test (cut-off: \(p\) < 0.05) and fold difference (>1 [log2]) between metabolites of the mother-infant pair. The codes, BC and BM, represent samples of the infant and the mother, respectively. been performed to explore the structure and function of human gut microbiota. This study used metagenomic sequencing to investigate the dynamic variation in the mother's and infant's gut microbiota, the interaction between intestinal microbiota, and the function of intestinal microbiota. The development of intestinal microbiota during the first 1000 days of life will affect a person's health throughout life [17,18]. Many factors determine the composition of intestinal microbiota in newborns. The method of delivery plays an important role in the initial establishment of infant gut microbes [19]. [PERSON] and colleagues proposed that vaginal delivery and exclusive reliance on breastfeeding in early life are the gold standards for the establishment and development of healthy gut microbiota in infants [20]. _Bifidobacterium, Bacteroides_, and _Clostridium_ proliferate and become the dominant genera associated with early life [21]. In the data we collected from our experiment, although _Bifidobacterium_ was not found in the intestine of the newborn, _Bacteroides_ was the dominant genus in the intestine. This was consistent with previous research. With the growth of the infant, the intestinal microbiota was more abundant, such as _Ruminococcus guavus_ and _Klebsiella Pneumonia_, among others. Nevertheless, before six months, _Bacteroides fragilis_ was still the highest relative abundance species in the infant's intestine, which was beneficial to maintaining the healthy environment of the intestine and worthy of continuous attention and exploration. Our data also showed that the gut microbiota composition of the infant was much less complicated than that of the mother, which was in line with the findings of previous studies [22]. Interestingly, we also observed differences in the richly differentiated taxonomic symbiotic network between the mother and infant. For example, in the infant's intestine, _Bacteroides fragilis_, _Methanobrevbincter smithii_, etc., were significantly positively correlated (\(p<0.05\)), while _Methanobrevbincter smithii_ generally appeared in the intestine of adults [23]. After obtaining this result, we repeated the investigation on the mother and learned that the infant was fed a mixture of breast milk and infant formula milk powder. In the study by [PERSON] et al., breastfeeding was one of the main factors affecting the early development of intestinal microbiota in infants [24], which confirmed the important influence of breastfeeding on the development of intestinal microbiota in infants. For mixed infants, the composition of infant formula milk powder was very different from breast milk. For example, infant formula milk powder lacked key compounds found in human breast milk, such as HMOs [25], which caused the intestinal microbiota of infants fed formula milk powder and breast milk to be very different [26].