Differences Of Fecal Microbiota In Infants With Different Feeding Patterns

The normal gut microbes play an important role in human digestion, immunity and disease resistance. Adult intestinal flora is mainly determined by colonization of the intestinal flora, while infancy is a critical period of colonization. Feeding patterns in infancy is one of the most important factors affecting colonization of the intestinal flora. Attempts to identity differences among gut microbes from breast-fed and formula-fed have generated controversial results at the moment. So it has been a hot point in the research of infant nutrition at home and abroad. Meanwhile there are already many studies showing that some microbe-mediated diseases including diarrhea, necrotizing enterocolitis (NEC), and allergic diseases are closely related to the feeding patterns of infant. Therefore, high-throughput sequencing technology is needed to clearly identify the differences of infant intestinal flora between breast-fed and formula-fed infants to more comprehensively understand the intestinal flora of infants with different feeding patterns, and to illustrate the relationship between feeding patterns and infant health and disease.24stool specimens of1-6months infants were collected, including breast-fed group (12),mixed-fed group (8), formula-fed group(4). Genomic DNA was extracted from samples by QIAamp of DNA stool mini kit and Illumina high-throughput sequencing technology was used to sequence V6variable region of the16SrRNA gene. The results showed that there was a high diversity in infant fecal flora,461species were detected. But the diversity was different in infants with different feeding, formula-fed and mixed-fed infants had a higher diversity than breast-fed infants. Gene sequence classification showed that more than98.9%of the sequences were found to belong to the four most populated bacterial phyla: Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. At the level of phylum, Firmicutes and Proteobacteria were dominant bacterial phyla in all three groups.The OTU species annotation selected "family" as the best level of classification. At the level of family,13family which richness was more than1%were detected. Enterobacteriaceae, Veillonellaceae, Bacteroidaceae were predominant bacteria in the intestinal microbiota of breast-fed infants, followed in turn by Bifidobacteriaceae, Streptococcaceae, Lachnospiraceae.While in formula-fed group and mixed-fed group, Enterobacteriaceae and Streptococcaceae were dominant bacteria, followed by Bifidobacteriaceae, Bacteroidaceae, Vibrionaceae, Veillonellaceae, Porphyromonadaceae, Lachnospiraceae in Mixed-fed group and Lactobacillaceae Clostridiaceae, Peptostreptococcaceae, Veillonellaceae, Lachnospiraceae, Vibrionaceae, Enterococcaceae, Erysipelotrichaceae in formula-fed group. The principal component analysis showed that bacteria contributing to sample differences were mainly Enterobacteriaceae, Veillonellaceae, Bacteroidaceae and Bifidobacteriaceae. Enterobacteriaceae were dominant bacteria in all three groups, but its proportion in formula-fed group (50.82%) was significantly higher than breast-fed group (28.66%), mixed-fed group was41.44%. the relative abundance of Veillonellaceae and Bacteroidaceae in breast-fed group(21.42%and12.82%) were significantly higher than mixed-fed group (3.65%and4.32%) and formula-fed group (3.25%and0.04%); the relative abundance of Bifidobacteriaceae in breast-fed group were only about8%,though it was not dominant bacteria, but higher than formula-fed group (1.48%). The fecal flora of formula-fed infants was diversification, the proportion of Lactobacillaceae, Clostridiaceae, Peptostreptococcaceae Enterococcaceae, Erysipelotrichaceae in the fecal flora ranged from2%to6%respectively, but it was low in breast-fed infants (0-3%)and mixed-fed infants(0-1%).Beta diversity and cluster analysis showed that there were large differences among samples within group. For further analyzing dynamic development of the intestinal flora of infant within1-6months, Statistical analysis of species richness of all sample was carried. The results showed that the intestinal flora structure of the three groups was simple before3months, and3months later, began to complicate. Especially the composition of intestinal flora of Mixed-fed infants had a greater change in the three months before and after. In1-3months, Enterobacteriaceae and Streptococcaceae were dominant bacteria, similar to the intestinal flora structure of formula-fed infants; in4-6months, the number of Bacteroidaceae, Porphyromonadaceae, Bifidobacteriaceae, Lachnospiraceae increased obviously to make the intestinal flora structure similar to breast-fed infants. In addition, in1to3months, the proportion of Enterobacteriaceae and Streptococcaceae in the intestinal flora of mixed-fed(44.53%and33.97%) and formula-fed infants(62.19%and20.77%) was significantly higher than breast-fed infants (26.75%and8.09%), while they were similar in the three groups respectively in4-6months.In this paper, it was concluded that there were differences of intestinal microbial flora of1-6months infants with different feeding patterns proved by high-throughput sequencing technology, there were more Veillonellaceae and Bacteroidaceae in the intestinal microbiota of breast-fed infants,while formula-fed and mixed-fed infants tended to have more Enterobacteriaceae and Streptococcaceae.The results not only provide a theoretical and technical support for future studies of infant intestinal flora, but also enable us to have a more comprehensive understanding of the intestinal flora structure of breast-fed and formula-fed infants to provide important resource for the study of feeding patterns and infant bowel disease.