Fine-scale bacterial community dynamics and the taxa-time relationship within a full-scale activated sludge bioreactor

George F. Wells, Hee Deung Park, Brad Eggleston, Christopher A. Francis, Craig S. Criddle*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

134 Scopus citations


In activated sludge bioreactors, aerobic heterotrophic communities efficiently remove organics, nutrients, toxic substances, and pathogens from wastewater, but the dynamics of these communities are as yet poorly understood. A macroecology metric used to quantify community shifts is the taxa-time relationship, a temporal analog of the species-area curve. To determine whether this metric can be applied to full-scale bioreactors, activated sludge samples were collected weekly over a one-year period at a local municipal wastewater treatment plant. Bacterial community dynamics were evaluated by monitoring 16S rRNA genes using Terminal Restriction Fragment Length Polymorphism (T-RFLP), corroborated by clone libraries. Observed taxa richness increased with time according to a power law model, as predicted by macroecological theory, with a power law exponent of w = 0.209. The results reveal strong long-term temporal dynamics during a period of stable performance (BOD removal and nitrification). Community dynamics followed a gradual succession away from initial conditions rather than periodicity around a mean " equilibrium" , with greater within-month then among-month community similarities. Changes in community structure were significantly associated via multivariate statistical analyses with dissolved oxygen, temperature, influent silver, biomass (MLSS), flow rate, and influent nitrite, cadmium and chromium concentrations. Overall, our results suggest patterns of bacterial community dynamics likely regulated in part by operational parameters and provide evidence that the taxa-time relationship may be a fundamental ecological pattern in macro- and microbial systems.

Original languageEnglish (US)
Pages (from-to)5476-5488
Number of pages13
JournalWater Research
Issue number17
StatePublished - Nov 1 2011


  • 16S rRNA
  • Activated sludge
  • Microbial community dynamics
  • Multivariate statistics
  • T-RFLP
  • Taxa-time relationship

ASJC Scopus subject areas

  • Water Science and Technology
  • Ecological Modeling
  • Pollution
  • Waste Management and Disposal
  • Environmental Engineering
  • Civil and Structural Engineering


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