# Describe how a fermenter is used to produce penicillin from Penicillium, and explain why the conditions inside the fermenter must be carefully controlled.

> Cambridge International IGCSE Biology (0610) — 21.2 Biotechnology · Describe and Explain · 4 marks

## Mark scheme (4 marks)

1. Penicillium is cultured / grown in a liquid nutrient medium inside the fermenter
2. Penicillin is secreted by Penicillium and is then isolated / extracted and purified
3. Temperature must be maintained at the optimum (25–30 °C) so that the microorganism is not killed / grows at the maximum rate
4. pH must be controlled at the optimum so the microorganism is not killed / to prevent growth being inhibited; OR undesired microorganisms must be excluded / killed to prevent contamination and 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)

## Related

- [Revision notes for Cambridge International IGCSE Biology (0610)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-a-fermenter-is-used-6374c057) · Published by Druglandscape Ltd.