Fermenters

This lesson covers:

  1. What industrial fermentation is
  2. Why and how we maintain suitable conditions in the fermenter
  3. The conditions in the fermenter

Industrial fermentation 


Microorganisms, such as bacteria and fungi, can be used to create valuable substances, such as penicillin, insulin, mycoprotein or yoghurt. 

To ensure their optimal growth, these microorganisms are grown in large tanks known as fermenters, where conditions like temperature, pH, and nutrient levels can be monitored and controlled at all times.


When done on a large scale, we call this process industrial fermentation.

Industrial fermenters

Diagram of an industrial fermenter showing stirring motor, microorganisms in, nutrients in, pH recorder, temperature recorder, water in, waste gas, water out, paddles, water-cooled jacket, air, and product out.
  1. Nutrients - added to the culture medium to support the growth and metabolic activity of microorganisms.
  2. pH probe - monitors and controls the pH during the fermentation process. An optimal pH range keeps the microorganism's enzymes working efficiently and maintains a high rate of reaction.
  3. Temperature probe - monitors the temperature within the fermenter and keeps it at an optimum level to maintain a high rate of reaction and prevent enzyme denaturation.
  4. Water-cooled jacket - surrounds the vessel and helps control and stabilise the temperature inside the fermenter.
  5. Air pump - introduces air (containing oxygen) into the fermenter. This is crucial for aerobic fermentations, where microorganisms require oxygen to respire.
  6. Paddles (or 'agitators') - used for mixing and ensuring uniform distribution of nutrients within the culture medium, promoting the growth of microorganisms and increasing the rate of reaction.

Sterilisation of fermenters


Industrial fermenters are designed to facilitate the sterilisation of vessels before introducing the culture medium and microorganisms. Sterilisation is essential to prevent contamination and ensure a controlled environment for the growth of microorganisms.

What is the primary purpose of industrial fermentation?

Enhancing product flavour in food processing

Using microorganisms to transform raw materials into valuable products

Regulating temperature in industrial settings

Extracting minerals from raw materials

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In which type of fermentation process is the introduction of oxygen necessary?

Aerobic fermentation

Anaerobic fermentation

pH-regulated fermentation

Temperature-controlled fermentation

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Why are paddles or agitators used in a fermenter?

To regulate temperature

To control pH levels

To sterilise the vessel

To mix and distribute nutrients in the culture medium

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In a fermenter, what is the role of a water-cooled jacket?

Mixing the culture medium

Controlling pH levels

Sterilising the vessel

Regulating temperature

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Why is the addition of nutrients in a fermenter crucial?

To add oxygen to the liquid medium

To extract final products

To support the growth and metabolism of microorganisms

To control pH levels

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