Activated Sludge Metagenome

Biogeochemical cycles are primarily driven by microbial activity, and the continually increasing anthropogenic impact on the biosphere calls for a better understanding of microbial community assembly mechanisms in response to human-induced disturbances. To examine such mechanisms we combined microbial community and functional analysis using bioreactors subject to a range of disturbances in the form of a toxic pollutant. Combining distance-based methods and null model analysis, we found that neutral assembly processes prevailed amongst intermediate disturbance levels leading to higher ?-diversity. We observed trade-offs in community function between organic carbon removal and both nitrification and biomass productivity. We propose the “Intermediate Neutrality Hypothesis”, which combines the neutrality component with the higher diversity of intermediately disturbed ecosystems, while expanding theories of post-disturbance community assembly. This framework should offer new opportunities for biodiversity conservation efforts upon environmental change.