<qa>  What is the human gut microbiota of a healthy adult?Throughout the human lifetime, the intestinal microbiota performs vital functions, such as barrier function, metabolic reactions, trophic effects, and maturation of the hosts innate and adaptive immune responses. Therefore, the human health depends on the gut health. It is reported that the human gut microbiota of a healthy adult is highly resilient and very stable over time. And before it reaches maturity, the microbiota must develop itself from birth and establish its mutually beneficial cohabitation with the host. However, the early developments of the microbiota in infants are influenced by many factors, such as prenatal parameters, the influence of the mother and her microbiota, and therapies occurring around the time of birth. 