AN ILLUSTRATIVE VIEW OF THE GUT MICROBIOME
Obtaining the Gut Microbiome
Pregnancy
Bacteria present in placenta, umbilical cord and amniotic fluid
It was widely believed that bacteria first colonised the gut at birth, however, recent studies have demonstrated the presence of bacteria in the placenta, amniotic fluid and umbilical cord. It is thought that the bacteria enters the gut through swallowing of the amniotic fluid.
Mode of Delivery
After first colonisation during pregnancy, the second stage in obtaining the gut microbiome is through the mode of childbirth, whether it be naturally or caesarean.
Each new-born will encounter different microbes due to the varying areas of contact and the specific microbes that exist there.
Natural born babies have a gut microbiome that resembles the mother's vaginal bacteria.
Caesarean born babies have a gut microbiome that resembles the mother's skin bacteria.
Infant Feeding
Breast milk is packed with sugars that influence bacterial gene expression for sugar foraging
First feeding methods may vary due to the choice of the mother. The gastrointestinal tract of breast fed infants tends to be dominated with Bifidobacterium ,compared to formula fed infants which show a more diverse microbiome consisting of increased Bacteroides, Enterobacteria, Enterococcus and Clostridia.
Age
From birth to 3 years of age, the bacteria composition is unstable with Bifidobacteria dominating the gut. The bacterial diversity increases into adulthood and remains stable until old age, where the diversity decreases again. This can be explained by the low mobility of elders which alters faecal transit and disturbs the bacterial composition.
