Exercise_ETH/Uni12 - koka - 1 h - basic

ETH/Uni12_Continuous culture: interpretation of experimental data.

After working on this exercise you will be able to....

1. prepare x(D) and s(D) diagrams for chemostat cultures starting from experimental data.

2. predict the influence of sin and of the growth parameters on x(D) and s(D) curves.


Determine the nature of the task.

2 Open the x,s(D)-simulation (Excel). Simulation > Kontinuierliche Kultur - Chemostat > Files

Take sin from the protocol.


Calculate Yx/s and µmax from the results of the batch experiment.

5 Determine Ks using the µ(s)-graph of Kovarova et al. (1996). Example > Batchwachstum - unbeschränktes Wachstum und kinetische Limitation > Graphs

Simulate x(D) and s(D) using the growth parameters and sin determined above.


Normalize the biomass concentrations measured during steady-state growth to the glucose concentration in the feed given in the protocol.

8 Calculate the exact dilution rates using the flow rates applied and the volume of the cultivation liquid measured at the end of the experiment.
9 Introduce the residual glucose concentrations and the normalised biomass concentrations as a function of D into the Excel sheet x,s(D) simulation and compare with the x(D) and s(D) graphs simulated beforehand.
10 Change Yx/s, µmax, Ks and ms so that the best fit of simulated and measured curves is obtained.
11 Formulate the mathematical model that describes best the experimental data of the chemostat experiments.
12 For each steady-state calculate the specific glucose consumtion rate qs, the yield Yx/s and the avareage dry weight per cell and represent the results as a function of D in an Excel graph. Example > Batchwachstum - Versuchsauswertung > How To 1

Summarise the results of all chemostat experiments.