Biotechnology

Question 1

Why are microorganisms often used in biotechnology?

Answer 1

• Grow rapidly if conditions are favourable.
• Can be genetically engineered.
• Grow well at low temperatures.
• Grow in any climate.
• Generate more pure products than chemical processes.
• Grow on waste nutrient materials.

Question 2

What is biotechnology?

Answer 2

It is the industrial use of living organisms to produce:
• Food
• Drugs
• Other products

Question 3

What is happening during the lag phase of a growth curve?

Answer 3

• Adjusting to environment.
• Cells growing.
• Protein synthesis.
• Respiration.
• The cells are active but not reproducing so population remains fairly constant

Question 4

What is happening during the log phase of a growth curve?

Answer 4

• Microorganisms reproducing

* Population doubles every generation (roughly every 20 mins)

Question 5

What is happening during the stationary phase of a growth curve?

Answer 5

• Rate of reproduction = Death Rate (DR)
• Limiting factors - Nutrients 
              - Space 
              - Build up of waste 
• Population size reaches the carrying capacity

Question 6

What is happening during the death phase of a growth curve?

Answer 6

• Death rate exceeds the rate of respiration

    - No space 
    - No nutrients 
    - Waste products have reached a toxic level

Question 7

How might population growth be affected if nutrients were added in the lag phase?

Answer 7

Unlikely to have an effect as nutrients are not limiting in the lag phase

Question 8

How might population growth be affected if nutrients were added in the stationary phase?

Answer 8

• increase in growth as nutrient supply likely to be limiting
• but if limiting factors space or waste build up then increasing nutrients unlikely to have an effect

Question 9

How might population growth be affected if waste products were removed in the stationary phase?

Answer 9

• increase in growth as accumulation of waste could be limiting
• but if limiting factors lack of nutrients or space then removing waste unlikely to have an affect

Question 10

What are primary metabolites?

Answer 10

• substances produced by an organism as part of its normal growth
• e.g. amino acids, enzymes, proteins, nucleic acids
• production matches normal growth

Question 11

What are secondary metabolites?

Answer 11

• substances produced that are not part of normal growth
• e.g. Antibiotics
• production begins after main growth so does not match population growth

Question 12

What is batch culture?

Answer 12

• where a starter population of microorganisms is supplied with a fixed amount of nutrients in and allowed to grow
• at the end of the time period the products are extracted

Question 13

What is continuous culture?

Answer 13

• where a culture is set up and nutrients are added and products removed from the culture at intervals
• the culture is maintained at the exponential phase of the standard growth curve so that it continues to grow and produce its metabolites quickly

Question 14

What are the advantages and disadvantages of batch culture?

Answer 14

• extra nutrients are not added (will eventually run out)
• waste products are not removed (good for producing secondary metabolites)
• slower growth because nutrient level declines with time
• easy to set up and maintain
• contamination only affects the batch

Question 15

What are the advantages and disadvantages of continuous culture?

Answer 15

• good for production of primary metabolites
• growth is higher as nutrients are continuously added
• more costly to maintain
• contamination is more costly as all product is lost
• more efficient as only has to be set up once and runs continuously

Question 16

How is pH manipulated in a fermentation vessel in order to maximise the yield?

Answer 16

• pH is monitored and kept at the optimum level
–> increases the product yield because enzymes can work efficiently so the rate of reaction is kept as high as possible

Question 17

How is temperature manipulated in a fermentation vessel in order to maximise the yield?

Answer 17

• the temperature is kept at the optimum level by a water jacket that surrounds the vessel
• this increases the product yield because enzymes can work efficiently to the rate of reaction is kept as high as possible
• if the temp is too high enzymes would be denatured and if it was too low growth would be slowed

Question 18

How is the volume of oxygen manipulated in a fermentation vessel in order to maximise the yield?

Answer 18

• the volume of oxygen is kept at the optimum level for respiration by pumping in sterile air when needed
• this increases the the product yield because microorganisms can always respire to provide the energy for growth
• a lack of oxygen will lead to unwanted products of anaerobic respiration and a reduction in the growth rate

Question 19

How is the type and time of addition nutrient manipulated in a fermentation vessel in order to maximise the yield?

Answer 19

• growth of microorganisms requires a nutrient supply including sources or carbon, nitrogen and other essential vitamins and minerals
• the timing of nutrient addition can be manipulated depending on whether the process is designed to produce a primary or secondary metabolite

Question 20

What could be the effect of unwanted microorganisms contaminating a batch? (Importance of asepsis)

Answer 20

• may compete with culture microorganisms for nutrients and space
• reduce the yield of useful products from the culture
• may cause spoilage to the product
• may produce toxic chemicals
• may destroy the culture microorganism and their products

Question 21

What is asepsis?

Answer 21

• it is the practice of preventing contamination of cultures by unwanted microorganisms

Question 22

What aseptic techniques can be used to prevent the contamination of a culture?

Answer 22

• washing, disinfecting and steam cleaning all equipment including the fermenter
• using a fermenter made from polished stainless steel which prevents microbes from sticking to surfaces
• sterilising all nutrients before they are added to the fermenter which is usually achieved by steam or heat treatment
• making sure that any air or oxygen bubbled into the fermenter is free from microorganisms which is achieved using very fine filters