Öz
Breastfeeding is an important factor affecting early life microbiota composition. The effect of breastfeeding on the microbial composition of infants has been described 100 years ago and it has been shown that human milk oligosaccharides enhances the intestinal microbial composition, especially Bifidobacteria. As a result of recent new generation sequencing studies on human milk, it has been shown that human milk has microbiota content of its own. Previous studies on human milk microbiota composition, Streptococcus, Staphylococcus, Lactobacillus, Bifidobacterium, Enterococcus, and Propionibacterium are most abundant taxa. In addition, Veillonella, Propionibacterium, and Faecalibacterium, which can produce short chain fatty acids, have also been shown to be present in human milk. It was shown that the human milk microbiota content varies according to delivery mode and gestational age. There is a difference for bacterial composition of human milk between elective cesarean section and normal spontaneous birth. In addition to delivery mode and gestational age, maternal obesity, psychological status of mothers during pregnancy, and intrapartum antibiotics use may also alter the composition of human milk bacterial microbiota. We observed some changes that the human milk microbiota composition (bacteriome, virome, mycobiome) varies in caesarean delivery, premature, small for gestational age and large for gestational age groups, comparing the normal spontaneous delivery, as well as differences between transient and mature human milk. In addition, it has been shown that there is a change in microbiota content in case of hand-expression and pump expression of human milk. The source of the human milk microbiota is still unknown. Potential described source for human milk microbiota are the entero-mammary route of the mother, transfer from the mother’s skin, and/or infant’s oral microbiota. Regardless of the source of human milk microbiota, it has been clearly shown that human milk transferred to the infant’s gut and breastfeeding is one of the determinants of the infant’s intestinal microbiota. The results of the TEDDY study showed that the most important factor for microbiota composition was breastfeeding in the first 1000 days. Human milk oligosaccharides content including prebiotics, might affect the human milk microbiota and infant’s intestinal microbiota. Bifidobacteria were found to be predominant strain in the intestinal microbiota content of infants fed with breast milk, in a short period after birth. The microbiota composition of human milk content is thought to play a significant role in the development of the infant's immune system. It is thought that human milk has effects on the intestinal microbiota of the infant and therefore on the immune system, resulting with the protection from infectious and non-communicable diseases. Further studies will help to understand the interactions between breastfeeding-microbiome and immune ontogeny.