Chapter 2.3 - Biotechnology And Batch Cultures

Question 0

Biotechnology makes use of micro organisms - the use of fungi and bacteria is common because micro organisms :

Answer 0

1) grow rapidly in favourable conditions, being able to grow sometimes at a generation rate of just 30 mins.
2) often produce proteins or chemicals that are given out to the surroundings, which we can harvest.
3) can be genetically engineered to produce specific desired products

Question 1

What is biotechnology?

Answer 1

Biotechnology refers to the technological processes which involve the use of living organisms. Biotechnology can be utilised to help produce foodstuffs, drugs and many more products.

Question 2

What is a culture

Answer 2

A culture is a population of one type of microorganism that has been grown under controlled conditions.

Question 3

What is a closed culture

Answer 3

A closed culture is when growth takes place in a vessel that’s isolated from the external conditions- extra nutrients aren’t added and waste products aren’t removed from the vessel during growth. In such a closed culture, a population of microorganisms follows a standard growth curve.

Question 4

When growing conditions are favourable, for cultures, what do the microorganisms produce?

Answer 4

Primary metabolites - small molecules which are essential for the normal growth of microorganisms.

Question 5

When growing conditions are less favourable, for cultures, what do the microorganisms produce?

Answer 5

Secondary metabolites - products which are not essential for growth but are useful in other ways.

Question 6

Give an example of a secondary metabolite and explain why it helps microorganisms

Answer 6

The penicillin antibiotic - it is produced by the fungus penicillium which helps microorganisms to survive by killing the bacteria that would inhibit it’s growth.

Question 7

What is metabolism and metabolites when culturing

Answer 7

Metabolism is a process which the microorganisms undergo during the culturing and metabolites are the products - not the raw materials.

Question 8

Biotechnology makes use of microorganisms - the use of fungi an bacteria is common, why?

Answer 8

Fungi and bacteria grow rapidly in favourable conditions, being able to grow sometimes at a generation rate of just 30 mins

They often produce proteins or chemicals that are given out to the surroundings which we can then harvest

They can be genetically engineered to produce specific desired products

Question 9

What is fermentation

Answer 9

The culture of microorganisms within fermenters. The substances generated by the growth of microorganism cultures are separated and treated to produce the final useful product.

Question 10

How do fermenters create the optimum conditions for growth to maximise the yield of the desirable products? 5

Answer 10

The pH is monitored using a pH probe. This increases enzyme efficiency and therefore keeps the rate of reaction high to increase output

The temperature is kept at optimum temperature using a water jacket.

Microbes are kept in contact with fresh medium using paddles meaning microbes have constant access to nutrients

The volume of oxygen is kept at the right level for aerobic respiration. This raises the yield due to increased respiration so more energy for growth

Vessels are sterilised between uses with superheated steam to kill any unwanted organisms so no competition.

Question 11

What is batch culture

Answer 11

Batch cultures are produced by industrial fermenters an they produce metabolites in batches, so the starter culture is added with a set amount of growth medium and the culture is left to grow, until it is harvested and the microbes are removed. The vessel is emptied and ready to be used again.

Question 12

What is a continuous culture

Answer 12

A continuous culture has new nutrients added and waste products removed from the vessel at regular intervals, continuously. This is more useful for harvesting human hormones from bacteria such as insulin from e.coli.

Question 13

Batch culture

Answer 13

A fixed volume of growth medium is added to the fermentation vessel at the start of the culture and no more is added - it is a closed culture

Each culture goes through lag, exponential, stationary and death phases.

Product is harvested once, during the stationary phase

Used when you want to produce secondary metabolites.

Question 14

When would you use batch culture?

Answer 14

When you want to produce secondary metabolites

Question 15

Continuous culture

Answer 15

Growth medium flows through the vessel at a steady speed rate so there is a constant supply if fresh nutrients - it is an open system.

The culture beings with the lag phase but is then maintained at the exponential growth phase

Used when you want to harvest the primary metabolites or the actual microbes themselves.

Question 16

When would you use continuous culture?

Answer 16

When you want to harvest primary metabolites or the actual microbes themselves.

Question 17

What is esepsis?

Answer 17

This is the practice of preventing contamination of cultures from unwanted biological microbes.

Question 18

Why is asepsis important?

Answer 18

Contamination of microbes will affect their growth. Also in a lab experiment, an infected test culture can provide inaccurate results and give invalid conclusions

Question 19

Why is contamination a disadvantage to a company?

Answer 19

It is expensive as the entire culture needs to be disposed of which means a large amount of wastage

Question 20

Give four asepsis techniques when dealing with microbes

Answer 20

1) washing, disinfecting and steam cleaning the fermenter regularly
2) fermenter surfaces are made of a polished stainless steel which is impenetrable and easy to clean
3) sterilising the nutrient medium before adding it To the fermenter
4) fine filters on all inlets and outlets on the fermenter to prevent entry of unwanted microbes