6.4.6 other processes involving biotechnology

Question 1

what does commercial drug production use

Answer 1

large stainless steel containers = fermenters

Question 2

conditions which must be controlled in a fermenter & why

Answer 2

• temperature = too hot & enzymes denature or too cold & growth will be limited
• nutrients available = microorganisms need nutrients to grow & synthesise the product –> sources of carbon, nitrogen, minerals & vitamins are needed
• oxygen availability = most organisms respire aerobically
• pH = enzyme activity, hence growth & synthesis are affected by extremes
• concentration of product = if product allowed to build up, it may affect synthesis process

Question 3

what should happen to the fermenter first

Answer 3

• sterilised using superheated steam
• then, filled with components required for growth & supplied with starter culture of microorganisms
• culture left to grow & synthesise products

Question 4

name the components of a fermenter

Answer 4

1. pressure vent = prevents gas build-up
2. air inlet = sterile air provides oxygen in aerobic fermenters
3. mixing blades
4. water jacket inlet = allows circulation of water around fermenter to regulate temperature
5. outlet tap for draining fermenter
6. motor = rotates blades to mix culture evenly
7. inlet for addition of nutrients
8. water jacket outlet
9. electronic probes = measure oxygen, pH & temperature levels
10. air outlets (often in a ring) = air bubbles out from outlets, mixing with culture (sparging)

Question 5

what are all inlets & outlets fitted with

Answer 5

filters = prevent contamination

Question 6

define primary metabolites

Answer 6

products which are synthesised by the microorganism during normal metabolism when they are actively growing

Question 7

describe continuous culture

Answer 7

• primary metabolites are continually released from cells & can be extracted continuously from fermenting broth
• broth topped up with nutrients as these are used by the microorganisms
• some of broth removed regularly to extract the product & remove cells from the broth (otherwise population becomes too dense)
• keeps microorganisms growing at specific growth rate

Question 8

define secondary metabolites

Answer 8

products which are produced only when cells are placed under stress eg. high population density or limited nutrient availability
–> produced mostly during stationary phase of growth

Question 9

describe batch culture

Answer 9

• culture set up with limited quantity of nutrients & allowed to ferment for specific time
• after this time, the fermenter is emptied & product can be extracted from culture

Question 10

importance of asepsis: why would the unwanted microorganisms reduce production?

Answer 10

• compete with cultured microorganisms for nutrients & space
• reduce yield of useful products
• spoil the product

Question 11

importance of asepsis: what may the unwanted organisms also do?

Answer 11

• produce toxic chemicals
• destroy cultured microorganisms & their products