Question

Draw labelled graphical representations of Batch and continuous culture systems.

Hint:

To prevent wash-out in a continuous culture, the dilution rate ($D$) must never exceed the microorganisms' maximum specific growth rate ($\mu_{\max}$), otherwise cells will be siphoned out faster than they can divide.

Answer 1

Step 1: Concept
Batch and continuous fermentation systems show distinct growth curves when plotting cell concentration over time.

Step 2: Graphical Layout Representation
The growth curves for both systems can be modeled and compared as follows:

Step 3: Description of Graphs
- Batch Culture Curve: Exhibits a classic S-shaped (sigmoid) curve with four distinct phases:
1. Lag Phase: Slow initial growth while cells adapt.
2. Log/Exponential Phase: Rapid cell division at maximum rate.
3. Stationary Phase: Growth rate equals death rate as nutrients deplete.
4. Death Phase: Cell count declines due to toxic buildup and starvation.
- Continuous Culture Curve: After a brief lag and log phase, the curve flattens into a continuous steady-state plateau, where cell concentration and nutrient levels remain constant over time.
Final Answer:
The comparative growth curves are illustrated in Figure.