Conditional confined oscillatory dynamics of Escherichia coli strain K12-MG1655 in chemostat systems (2012)

Author(s): Ofiteru ID, Ferdes M, Knapp CW, Graham DW, Lavric V

    Abstract: A series of batch and continuous-low experiments were performed to assess growth dynamics of Escherichia coli strain K12-MG1655 in bioreactors. Previous mathematical predictions and early experimental results had shown that confined oscillatory dynamics occur in reactor populations that relates to time-delayed “birth and group death” events within the population. New results are reported here that generally verify predictions of the model and show that confined oscillations occur from different initial conditions, but the character of oscillatory dynamics varies as a function of hydraulic retention time (HRT). Bioreactors were operated with HRTs ranging from 2.7 to 35 hours and, regardless of start-up conditions or the imposition of transient operational instabilities, highly patterned oscillations ultimately developed when HRT was between ~ 3 and 8 hr. However, outside of this range, reactor populations tended to form biofilms on the reactor walls (rather than discrete growth in the bulk solution) and stable oscillations were not seen in the bulk phase. This suggests that alternate operating “states” might exist in reactor populations with biofilm formation and non-homogenous spatial growth patterns dominating system behaviour at low and high HRTs. Although the model predicts a confined dynamic equilibrium, data here show that such dynamics only occur at mid-range HRTs because biofilm formation dominates system behaviour outside of this range.

      • Date: 15-11-2011
      • Journal: Applied Microbiology and Biotechnology
      • Volume: 94
      • Issue: 1
      • Pages: 185-192
      • Publisher: Humana Press, Inc.
      • Publication type: Article
      • Bibliographic status: Published

      Professor David Graham
      Professor of Ecosystems Engineering