Two students look at two bioreactors. Reactor A has a cylindrical vessel with a motor and a shaft…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Two students look at two bioreactors. Reactor A has a cylindrical vessel with a motor and a shaft with blades, and no inlet at the bottom. Reactor B has the same, and also a pipe that brings sterile air to a ring at the bottom of the vessel.
- Name each reactor.
- In which reactor does the oxygen reach the cells by the bubbles, and what does the stirrer do in the other one?
- Why must the air of reactor B be sterile?
Need a reminder? The key ideaShow
A stirred-tank reactor mixes with a stirrer. A sparged stirred-tank reactor also bubbles sterile air. The parts are the agitator, the oxygen delivery, the foam control, the temperature control, the pH control and the sampling ports. Air flow volume air rate. Product of a batch volume product in each litre.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Two reactors.
Plan. Look for the bubbles of air.
Step 1. (a) Reactor A is a simple stirred-tank bioreactor. Reactor B is a sparged stirred-tank bioreactor.
Step 2. (b) In reactor B, sterile air is bubbled in, and the bubbles give oxygen. In reactor A, the stirrer mixes the culture evenly and also makes oxygen available throughout the vessel. B has a stirrer as well.
Step 3. (c) Unsterile air would bring in other microbes, which would grow beside the wanted cells and spoil the product.
Answer: (a) A is a stirred-tank reactor and B is a sparged stirred-tank reactor. (b) By bubbles in B. In A the stirrer mixes and makes oxygen available. (c) To keep other microbes out.
Watch out. A sparged reactor is also a stirred reactor. The difference is the extra bubbling.
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