1. Metabolites – primary and secondary

2. Learning Outcomes Compare and contrast the processes of continuous culture and batch culture. Describe the differences between primary and secondary metabolites.

3. Metabolism and metabolites Metabolism (process) Sum total of all the chemical reactions Processes produce New cell and cell components Chemicals Waste products Metabolites (products) A substance produced during cell processes

4. Primary and secondary metabolites Primary metabolite Substance produced by organism as part of it’s normal growth E.g. amino acids, proteins, enzymes Production of primary metabolites matches the growth in population Secondary metabolite A substance only produced at a particular growth phase No direct involvement in fundamental metabolite processes Production usually begins after the main growth phase of the micro organisms

5. Primary Metabolites Primary metabolites are produced during active cell growth [lag, exponential, stationary], matches the growth in population of the organisms Produced by all microorganisms

6. Secondary Metabolites Secondary metabolites are produced near the onset of stationary phase e.g antibiotic chemicals Not produced by all microorganisms

7. Batch culture Starter population is mixed with a specific quantity of nutrient solution Allowed to grow for a fixed period Products removed Fermentation tank emptied Examples Penicillin production Enzyme production

8. Continuous Culture Nutrients are added and products are removed from the fermentation tank at regular intervals Examples Insulin production from genetically modified E.Coli Production of mycoprotein

9. A batch fermenter

10. Why use Batch? Many secondary products are not growth associated Genetic instability Operability and reliability Economic considerations

11. Exam Practice – Unit 5 questions 99, 125, 141, 170

12. Q141 Unit 5 questions

14. Primary metabolites Secondary metabolites A fermenter