Study of the competition between complete nitrification by a single organism and ammonia- and nitrite-oxidizing bacteria

Abstract

Complete nitrification by only one microorganism has been recently experimentally discovered. However, it was theoretically predicted almost 10 years ago by hypothesizing that complete nitrifiers are yield strategist that have a metabolic advantage to survive in biofilms. In this work, we study the competition for ammonia between complete nitrifiers and the canonical division of labour between ammonia and nitrite oxidizing bacteria in biofilms by using an individual based model. The model calculates the maximum growth yield using thermodynamics to evaluate the limitation in growth for each functional group in each position of the computational domain. Our results suggest that the trade-off between growth yield and growth rate in ammonia oxidizing bacteria and in complete nitrifiers is not significant as to observe a clear advantage for complete nitrifiers existence in biofilms.