Correlations Between The Gut Microbiota Of Newborns And Microbial Communities Of Multiple Body Habitats In Mothers

The humans and their indigenous microbial communities have coevolved intricate and intimate mutual relationships,resulting in the concept of"Supraorganism".Infant gut microbial origin and colonization are important and complex processes.Over a century ago,researchers proposed that fetus developed in the sterile environment of womb,and the establishment of human neonatal microbiota has been seen as commencing at birth.However,increasing evidence suggests that the seeding process actually occurs initially in utero,and fetus may be acquired its microbiota from maternal vaginal,intestinal tract,oral cavity,amniotic fluid,placenta,mammary gland and skin micro ecological environment.But comprehensive studies on the transmission of microbes from mother to infant have been rarely reported.In the present study,the microbial community structure of maternal and fetal samples(meconium,maternal feces,amniotic fluid,vaginal fluid,breast milk and the saliva)collected from 41 healthy volunteer mothers and infants were analyzed using Pacific Biosciences(PacBio)single-molecule,real-time sequencing technology(SMRT)and droplet digital polymerase chain reaction(ddPCR).The goal of this study was to find out the origin of human gut microbiome and the transmission of gut microbes from mother to infant.The results showed that the predominant phyla of meconium,maternal amniotic fluid,vaginal fluid and breast milk were Firmicutes and Proteobacteria,and the predominant phyla of maternal feces and salivawere Firmicutes and Bacteroidetes.The relative abundances of Proteobacteriain meconium was significantly higher than those in maternal feces,while Bacteroidetes in meconium was significantly lower than maternal feces.The result showed that meconium microbes structure was more similar with those of maternal amniotic fluid,vaginal fluid and breast milk at phylum level.The flora similarity analysis based on OTU level demonstrated that the flora similarity of meconium,maternal amniotic fluid,vaginal fluid and breast milk was significantly higher than those from other maternal samples.This result revealed that the gut microbial structure of early life was closely related to maternal amniotic fluid and vaginal fluid microbiota,resulting in microbial colonization of the fetal gastrointestinal tract by fetal ingestion of amniotic fluid.This study also found that Lactobacillus diversity in the meconium of infants who were given birth naturally was higher than those underwent Caesarean section.There was significant similarity(p<0.001)between meconium and maternal vaginal fluid microbiota based on nature delivery,suggesting microbial contact of the neonatal gastrointestinal tract with maternal microbiota during perinatal period.ddPCR assays revealed that the amounts of Lactobacillus in the meconium of infantwho were given birth naturally were higher than those underwent Caesarean section(p<0.01),indicating that delivery mode influences the composition of early-life gut microbiota.Thus,neonates likely acquiring maternal vaginal fluid microbiotaby vertical transmission during natural delivery.To sum up,contacting with maternal amniotic fluid microbiota in utero is an original source of microbiota for colonization of the infant gastrointestinal tract,and various characteristics of infant intestinal microbiota were shaped by different delivery modes.