Module 6: Biotechnology 2

Question 1

What are the 2 main reasons for culturing microorganisms?

Answer 1

-to generate biomass of them for use in producing single cell protein for animal feedstock

-to manufacture compounds synthesised by them (antibiotics , enzymes etc)

Question 2

Make 1 point describing what primary , then what secondary metabolites are

Answer 2

primary metabolites-substances produced in processes that are essential for the microorganism to function

secondary metabolites-substances produced in non essential processes so aren’t essential for normal functioning

Question 3

What are bioreactors?
What are the 5 typical components of a bioreactor

Answer 3

large fermentation tanks used for large scale production of microbe cultures , they are optimised for microbial growth

-metal/plastic tank with inputs and outputs for liquids and gases
-paddles for mixing the culture to ensure even distribution of nutrients and oxygen
-probes to monitor pH , temp and dissolved oxygen
-ports for adding ingredients and removing products
-sterilisation system

Question 4

How is temperature controlled in a bioreactor?

Answer 4

there are heating and cooling jackets surrounding vessels

Question 5

What type of technique must be used when culturing microorganisms and why?

Answer 5

aseptic techniques , in order to prevent contamination of microorganisms with unwanted ones

Question 6

What are the 2 types of fermentation

Answer 6

Batch fermentation and continuous fermentation

Question 7

Make 2 points describing batch fermentation

Answer 7

microbes are grown in a fixed volume of nutrient broth in batches until nutrients deplete and waste products accumulate

each batched is emptied and the vessel is cleaned before starting the next batch

Question 8

Make 2 points describing continuous fermentation

Answer 8

involves continuously supplying new nutrients and removing culture broth

this maintains the growth of the culture indefinitely

Question 9

In batch cultures , microbes follow a …

Answer 9

standard growth pattern over time

Question 10

The 4 stages of microbial growth pattern in batch cultures are …

make 1 point explaining each

Answer 10

lag phase-cells have slow initial growth as they adapt to the environment and produce essential enzymes

log phase-rapid cell growth as they’ve adapted to the conditions and nutrient supply is plentiful

stationary phase-growth rate plateaus as nutrients diminish and waste accumulates
(cell growth=death rate)

death phase-cell death rate exceeds cell growth rate as due to resource limitations and build up of toxins