# Describe how fermenters are used to produce penicillin from the fungus Penicillium on a large scale. Include in your answer the conditions that must be controlled inside the fermenter and explain why each condition is important.

> Cambridge International IGCSE Biology (0610) — 21.1 Biotechnology and genetic modification · Describe · 4 marks

## Mark scheme (4 marks)

1. Penicillium is cultured/grown in a liquid nutrient medium inside the fermenter, and penicillin is secreted then isolated/purified.
2. Temperature must be controlled (typically 25–30 °C) because temperatures that are too high or too low will kill the microorganism / inhibit growth.
3. pH must be controlled/maintained at the optimum for Penicillium because pH that is too acidic or too alkaline will kill the microorganism / prevent growth.
4. Oxygen must be supplied / nutrients must be provided AND other microorganisms must be excluded to prevent contamination / competition.

## Key terms

- [fermenter](https://www.gradenine.co.uk/glossary/fermenter)
- [Penicillium](https://www.gradenine.co.uk/glossary/penicillium)
- [penicillin](https://www.gradenine.co.uk/glossary/penicillin)

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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-fermenters-are-used-to-87d941cf) · Published by Druglandscape Ltd.