Soil amoebae rapidly change bacterial community composition in the rhizosphere of Arabidopsis thaliana.

We constructed an experimental model system to study the effects of grazing by a common soil amoeba, Acanthamoeba castellanii, on the composition of bacterial communities in the rhizosphere of Arabidopsis thaliana. Amoebae showed distinct grazing preferences for specific bacterial taxa, which were rapidly replaced by grazing tolerant taxa in a highly reproducible way. The relative proportion of active bacteria increased although bacterial abundance was strongly decreased by amoebae.