| The intestinal microbiota turn into imbalance, the body will fall ill, especially in the infants, such as allergies, type II diabetes, abdominal pain, stomach cancer, infant autism, enteritis, anorexia or obese. There is no doubt that the establishment of the reasonable infant intestinal micro-ecology is the most important. Development of the intestinal microbiota in infants is characterized by rapid and large changes in microbial abundance, diversity, and composition. These changes are influenced by medical, cultural, and environmental factors such as mode of delivery, diet, familial environment, diseases, and therapies used. The strong influence in the development of the infant intestinal microbiota is the mode of feeding. Human breast milk is considered the best nutritional option for growth and health development of newborn infants; it can maintain the colonization of the normal neonatal gut microbiota and provide all the necessary nutrients to meet the growth of the baby. The quantity and quality of these nutrients can meet the needs of the metabolism of the newborn. The rates of breastfeeding from one country to another is more and more lower along with the development of society and the change of dietary structure, it will cause various influence for infant health. Newborn need artificial feeding, they are faced with severe infection and sepsis. Therefore, identifying the ideal structure of gut microbial ecology, simulating breast milk to alter the intestinal micro ecology, understanding the different and key intestinal microbiota between breast-fed and infant formula-fed infants before adding dietary supplement, developing new infant formula and solving the problem of less breast milk are imperative.In this context, researching the similarities and differences between the breast-fed and formula-fed infant intestinal microbiota before adding dietary supplement (3-6 months), and developing an infant formula closing to breast milk are very meaningful. Therefore, this research was as follows:the colonization of infant intestinal microbiota, and the relationship between it and feeding patterns using high-throughput sequencing were studied; an infant formula milk powder (low protein, high carbohydrate) was applied to regulate the physiological status and large gut microbiota of SD newborn rats, and compared with the breast-fed and the human breast milk fed SD newborn rats; the microbiota and metabolites of the breast-fed infant (6 months) feces and the large gut content from breast-fed SD newborn rats were analyzed, The results were shown as below:(1) More than 98.6% of ihe sequences in all the breast-fed and formula-fed samples were found to belong to the four most populated bacterial phyla that were Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. Differences were found in the proportions of the phyla:Actinobacteria, Bacteroidetes and Firmicutes were more represented in breast-fed than in formula-fed infants (10.42 vs. 2.60%,0.48 vs.0.12% ,66.04 vs.36.52% respectively), whereas Proteobacteria was more abundant in formula-fed than in breast-fed infants (60.44 vs.22.79%). Statistical analysis indicated that Firmicutes (p= 0.035) and Actinobacteria (p=0.047) significantly differentiate the breast-fed from the formula-fed infants, and that Proteobacteria (p=0.019). Enterobacteriaceae were the dominant bacteria in formula-fed infants. Veillonellaceae and Enterohacteriaceae were the dominant bacteria in the breast-fed infants. The percentage of Lactobacillaceae in formula-fed and breast-fed fecal microbiota was very low (4.12 vs.5.80%).The bacteria were rarely distinguished at the genus level, the number of genera identified (percentage of sequences<0.1%) in breast-fed and formula-fed infants was 17 and 15 respectively, and Streptococcus was the dominant bacterial genus in both groups. Breast-fed infants harbored two times Bifidobacterium compared to formula-fed infants.(2) In a 7 d intervention, a total of 36 neonatal SD rats (14 d old) were randomly assigned to the following groups:(1) SD rats’ breast-fed group (A group); (2) low-protein, high-carbohydrate infant formula-fed group (B group); (3) human breast milk-fed group (C group). After 7 days, we selected 6 rats at random from each group to study. Significantly different (p<0.05) in weight, gut organization and pH in the large intestines of SD rats’ breast-fed group was bigger than low-protein, high-carbohydrate infant formula-fed and human breast milk-fed rats, and SCFA was opposite that in three groups(p<0.001).The concentrations of ammonia were significantly higher for the SD rats’ breast-fed group than other groups (p<0.001). Protease activities after breast milk diet ingestion, were increased than infant formula-fed and human breast milk-fed group, it was significantly different (p<0.001). Microbial composition in the contents of the large intestines was analyzed by Miseq Sequencing. We found a high microbial diversity in the infant feces and detected 245 species at most, but the diversity of the infant intestinal microbiota with different feeding patterns was different; the diveristy of fecal microbiota from SD rats’ breast fed group was higher than other groups. The rarefaction curves, accumulation curves and Shannon-Wiener curves meant the database of 16S rRNA gene sequences was very abundant, that reflected the vast major of microbial information. All sequences were classified from phylum to genus; these bacterial OTUs can be assigned into 11 different phyla,44 families or 78 genera. Bacteroidetes, Firmicutes, Proteobacteria were common to the whole 18 libraries, which comprised 94.52%,97.11%,97.53% of the total reads in the libraries of breast-fed, infant formula-fed and human breast milk-fed groups. At family level, there were 6 shared families (abundance> 1%) among the total 44 families existed in all samples, namely, Acidaminococcaceae, Bacteroidaceae, Enterobacteriaceae, Erysipelotrichaceae, Lachnospiraceae, and Porphyromonadaceae. Detected OTUs were distributed among 78 different bacterial genera. Bacteroides was the most abundant division, comprising approximately from 1909 OTUs to 22073 reads across all samples, their mean OTUs abundance in SD rats’ breast-fed, infant formula-fed and human breast milk-fed groups was 14.91%, 35.94%,43.24% respectively. From the analysis of PCA, NMDS, Hierarchical heatmap and Venn diagram, we found SD rats’ breast-fed group had higher number of shared species, and high similarity of the communities were found infant formula-fed and human breast milk-fed groups. Compared with infant formula-fed and human breast milk-fed groups, mRNA levels for GADPH and aquaporin-8 were increased, but mRNA levels for Ubiquitin carboxyl-terminal hydrolase FAF-Y, AminopeptidaseA and CathepsinF were reduced. Rats from infant formula and human milk group suffered substantial stress, were forced fed, had no contact with adult rats, and were maintained in the same living circumstance, and the level of protein with high carbohydrate in formulas did have immediate consequences on gut ecology, we concluded the composition of the formula may be the factor causing similar microbiota profiles.(3) We found most bacteria belonged to the four phyla:Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. The abundance of Actinobacteria and Proteobacteria in infant was higher than SD newborn rats, but the abundance of Bacteroidetes and Firmicutes was smaller. The abundance of the families (>%1) in two groups was different, the number was 8 and 12 respectively. Bacteroidaceae and Erysipelotrichaceaee were shared bacteria; their abundance in infant was slightly higher than SD rats. The abundance of Bacteroides was not significantly different in the two groups, and it was smaller in infant. Bifidobacterium and Lactobacillus were significantly different in the two groups (p<0.01), the abundance of Bifidobacterium in infant was higher than in SD rats, but the abundance of Lactobacillus was contrary. The metabolites of the breast-fed infant (6 months) feces and the large gut content from breastfed SD newborn rats were different, glycerol and malonate were only observed in infant feces, but p-alanine was only visible in SD rats.The innovations of the study were:(1) The results revealed the similarities and differences between breast-fed and informua-fed infant (3-6 months) intestinal microbiota. (2) We used a low protein and high carbohydrate infant formula to simulate breast milk, compared the similarities and differences between SD rats’ and breast-fed infant intestinal microbiota and their metabolites, they could supply a animal model for developing infant formula and could provide us a new idea for future studies of the infant formulas. |
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