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Project 4B: A syntrophic bacterial consortium

Project assignment

Develop a coarse-grained model that

  • Quantitatively reproduces batch growth on glucose of the glucose specialist,
  • Qualitatively reproduces batch growth on acetate of the acetate specialist,
  • Qualitatively reproduces the behavior of a consortium of glucose and acetate specialists growing on glucose in a chemostat.

Biological question to be answered

What are the conditions for (i) the co-existence of the two strains and (ii) the occurrence of synthrophy, when the consortium is grown in a chemostat on glucose?

Quantitative data and qualitative observations to account for

  • Growth curves of the glucose specialist in standard batch conditions on glucose,
  • Overflow of acetate by the glucose specialist in standard batch conditions on glucose,
  • Toxic effect of acetate on growth rate.
  • Optional: dependence of acetate overflow on the glucose uptake rate

Model structure

Environment described by concentrations of biomass (B, gdW/L), glucose (G, g/L) and acetate (A, g/L) in a continuous culture of constant volume.

\[\frac{dB_{C}}{dt} = \mu_C B_C - DB_C \]
\[\frac{dB_{P}}{dt} = \mu_P B_P - DB_P \]
\[\frac{dA}{dt} = (r^a_{overP} - r^a_{upP}) B_P + (r^a_{overC} - r^a_{upC}) B_C - DA\]
\[\frac{dG}{dt} = -r^g_{upP} B_P - r^g_{upC} B_C + D (G_{in} - G)\]

where \(\mu\) is the growth rate (h⁻¹), D is the dilution rate (h⁻¹), \(r_{over}\) is the acetate overflow rate (g/gDW/h) and \(r_{up}\) (g/gDW/h) is the uptake rate.

Available data

The following data are available as csv files:

  • Growth of the glucose specialist on glucose in batch,
  • The effect of acetate on the growth rate of the glucose specialist.

The units are the same as described in the Model structure. Time is in hours.