22.7Culturing microorganisms an industrial scale

Question 1

What are primary metabolites

Answer 1

Substances that are wanted which are formed as an essential part of the normal functioning of a microorganism

Question 2

What are secondary metabolites

Answer 2

Organisms produce substances which are not essential for growth but are still used by cells
Organism wouldnt suffer without them

Question 3

What are teh 2 main ways of growing microorganisms

Answer 3

Batch fermentation

Continuous fermentation

Question 4

What are teh first 2 stages of batch fermentation

Answer 4

Microorganisms are inoculated into a fixed volume of medium

Growth will then begin to take place and the nutrients are used up and both new biomass and waste products build up

Question 5

What happens in batch fermentation when the culture reaches the stationary phase

Answer 5

Overall growth stops but microorganisms often carry out biochemical changes to form desired end product
The process is stopped before the death phase and the products are harvested

Question 6

What happens in continuous fermentation

Answer 6

Microorganisms are inoculated into sterile nutrient medium and start to grow
Sterile nutrient medium is added continuously to culture once it reaches exponential point of growth
And teh culture broth is continuously removed
This keeps the culture volume in the bioreactor constant

Question 7

How do we control bioreactors and why is it important

Answer 7

Important to maximise the yield of products required

Control -
Temp 
Nutrients and oxygen 
Mixing things up 
Asepsis - sealed in aseptic units