Conditional confined oscillatory dynamics of <Emphasis Type="Italic">Escherichia coli</Emphasis> strain K12-MG1655 in chemostat systems |
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Authors: | Email author" target="_blank">Irina?Dana?Ofi?eruEmail author Mariana?Ferde? Charles?W?Knapp David?W?Graham Vasile?Lavric |
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Institution: | (1) Chemical Engineering Department, University Politehnica of Bucharest, Polizu 1-7, 011061 Bucharest, Romania;(2) David Livingstone Centre for Sustainability, Department of Civil Engineering, University of Strathclyde, Glasgow, UK, G1 1XN;(3) School of Civil Engineering and Geosciences, Newcastle University, Newcastle Upon Tyne, NE1 7RU, UK |
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Abstract: | A series of continuous- and sequencing-batch reactor experiments were performed to assess the growth dynamics of Escherichia coli strain K12-MG1655 in chemostat systems. Previous mathematical predictions and early experimental results had shown that confined
oscillatory dynamics ensue in bioreactor populations, which relates to “group birth and death” events within the population.
New results are reported here that generally verify the predictions of the model and show that confined oscillations occur
under different initial conditions, but the characteristics of the oscillatory dynamics vary as a function of the hydraulic
retention time (HRT). Bioreactors were operated at HRTs ranging from 2.7 to 35 h and, regardless of initial conditions or
the imposition of transient operational instabilities, highly patterned oscillations developed when HRT was between ∼3 and
8 h. However, outside of this range, bioreactor populations tended to form biofilms on the reactor walls (although the majority
of the cells remained suspended in the bulk solution) and stable oscillations were not seen in the bulk phase. This suggests
that alternate operating “states” might exist in chemostat populations with biofilm formation and non-homogenous spatial growth
influencing “system” dynamics at very low and high HRTs. Although the model accurately predicts a confined dynamic equilibrium
for mid-range HRT operations, experimental data show that model predictions do not extend outside of this range, when an alternate
stable-state seems to be attained. |
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