A complex community of microbes develops in the infant gut shortly after birth. We call this community the infant gut microbiota. The microbiota influences the health of the infant, which makes the... Show moreA complex community of microbes develops in the infant gut shortly after birth. We call this community the infant gut microbiota. The microbiota influences the health of the infant, which makes the composition and function of the infant gut microbiota an important topic to study. It’s not possible to directly study the development of the microbiota inside the infant, so we are limited to information from fecal samples and laboratory experiments. Because it is so difficult to study, the processes and mechanisms that shape the microbiota also remain unclear. Mathematical models can generate hypotheses and predictions about the unseen inner workings of a system such as the infant gut microbiota.In this thesis we develop a mathematical model that makes predictions both on how bacteria are influenced by the environment and on how they influence the environment. By applying this influence to the environment and repeating the technique, the model can make predictions for how the whole system changes over time. We use this model to make predictions on how changes to the environment, such as the presence of oxygen, antibiotic disturbances, or in particular the presence of oligosaccharides, influence the infant gut microbiota, their metabolism, and ultimately the infant. Show less