Industrial fermenters
Fermenters are containers used to grow bacteria and fungi in large amounts, eg Penicillium mould for producing penicillin (an antibiotic).
Diagram of a fermenter
Fermenters are usually made from a metal that will not corrode, such as stainless steel. Some have the capacity to hold thousands of litres.
The table describes the main features and functions of a fermenter.
| Feature | Function | Reason |
| Steam inlet | Hot steam sterilises the inside of the fermenter | An aseptic precaution to prevent contamination by unwanted micro-organisms |
| Nutrient inlet | Allows sterile nutrients to enter the fermenter | Penicillium need nutrients so that they can grow and reproduce |
| Water jacket with cooling water | Keeps the temperature inside constant | Penicillium grow best at an optimum temperature of 23-28°C |
| Air inlet | Provides a source of oxygen | Penicillium need oxygen for aerobic respiration |
| Filter on air inlet | Stops micro-organisms getting inside the fermenter | An aseptic precaution to prevent contamination by unwanted micro-organisms |
| Stirring paddles | Keeps the mixture inside the fermenter agitated (stirred) | Mixes the micro-organisms with the nutrients and keeps the temperature even |
| pH probe and intake valve for acid and alkali | The pH inside the fermenter is monitored to check it is at the optimum value | Penicillium need to be maintained at pH 6.5, the optimum for the fungus |
| Feature | Steam inlet |
|---|---|
| Function | Hot steam sterilises the inside of the fermenter |
| Reason | An aseptic precaution to prevent contamination by unwanted micro-organisms |
| Feature | Nutrient inlet |
|---|---|
| Function | Allows sterile nutrients to enter the fermenter |
| Reason | Penicillium need nutrients so that they can grow and reproduce |
| Feature | Water jacket with cooling water |
|---|---|
| Function | Keeps the temperature inside constant |
| Reason | Penicillium grow best at an optimum temperature of 23-28°C |
| Feature | Air inlet |
|---|---|
| Function | Provides a source of oxygen |
| Reason | Penicillium need oxygen for aerobic respiration |
| Feature | Filter on air inlet |
|---|---|
| Function | Stops micro-organisms getting inside the fermenter |
| Reason | An aseptic precaution to prevent contamination by unwanted micro-organisms |
| Feature | Stirring paddles |
|---|---|
| Function | Keeps the mixture inside the fermenter agitated (stirred) |
| Reason | Mixes the micro-organisms with the nutrients and keeps the temperature even |
| Feature | pH probe and intake valve for acid and alkali |
|---|---|
| Function | The pH inside the fermenter is monitored to check it is at the optimum value |
| Reason | Penicillium need to be maintained at pH 6.5, the optimum for the fungus |
Once the Penicillium has been in the fermenter for around 200 hours, the liquid is removed and filtered. This removes fungal cells, leaving the product penicillin which will need to be treated chemically before use.