Variability in Microbial Community Structure during Development of a Nutrient-Cycling Model Ecosystem

Understanding, predicting and controlling the development of complex communities is a key goal of ecological science. In initially identical, but spatially segregated microbial communities that are allowed to develop under the same environmental conditions - for example, in parallel run bioreactors - effects of stochastic processes become critical. However, is it not yet known whether it would be possible to predict the final microbial community compositions of such populations once they have reached steady state. To address this, we used well-controlled microcosms containing nutrient-cycling microbial communities to study in detail the reproducibility of microbial community development. These closed, multiple replicate microcosms were constructed using the same source water and sediment and allowed to develop over several weeks under constant environmental conditions, after which, the microbial communities were characterised using Next Generation Sequencing. Our results show that microbial communities can follow alternative - yet stable - trajectories, diverging in time in a system size-dependent manner.Aims and Objectives:1. To follow trajectories of microbial community development in multiple replicate microcosms.2. To predict outcomes of stochastic processes on microbial communities.3. To test the effect of system size on microbial communities.