In vitro gut model systems permit the growth of gut microbes outside their natural habitat and are essential to the study of gut microbiota. Systems available today are limited by lack of scalability and flexibility in mode of operation. Here we describe the development of a versatile bioreactor module capable of sensing and controlling of environmental parameters such as pH control of culture medium, rate of influx and efflux of the culture medium, and aerobic/anaerobic atmosphere. Modules can be linked in series to construct a model of a digestive tract to allow the growth of microbiota in vitro. We tested the growth of a model bacterial community in a simulated mammalian gut model. The model attained and maintained a stable bacterial community that metabolized bile acids. The findings illustrate the utility of the model to grow to culture a mixed bacterial community and recapitulate biological activities such as bile acid metabolism in vitro.