Chapter 2.3 - Biotechnology And Batch Cultures Flashcards
Biotechnology makes use of micro organisms - the use of fungi and bacteria is common because micro organisms :
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
What is biotechnology?
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.
What is a culture
A culture is a population of one type of microorganism that has been grown under controlled conditions.
What is a closed culture
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.
When growing conditions are favourable, for cultures, what do the microorganisms produce?
Primary metabolites - small molecules which are essential for the normal growth of microorganisms.
When growing conditions are less favourable, for cultures, what do the microorganisms produce?
Secondary metabolites - products which are not essential for growth but are useful in other ways.
Give an example of a secondary metabolite and explain why it helps microorganisms
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.
What is metabolism and metabolites when culturing
Metabolism is a process which the microorganisms undergo during the culturing and metabolites are the products - not the raw materials.
Biotechnology makes use of microorganisms - the use of fungi an bacteria is common, why?
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
What is fermentation
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.
How do fermenters create the optimum conditions for growth to maximise the yield of the desirable products? 5
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.
What is batch culture
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.
What is a continuous culture
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.
Batch culture
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.
When would you use batch culture?
When you want to produce secondary metabolites
Continuous culture
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.
When would you use continuous culture?
When you want to harvest primary metabolites or the actual microbes themselves.
What is esepsis?
This is the practice of preventing contamination of cultures from unwanted biological microbes.
Why is asepsis important?
Contamination of microbes will affect their growth. Also in a lab experiment, an infected test culture can provide inaccurate results and give invalid conclusions
Why is contamination a disadvantage to a company?
It is expensive as the entire culture needs to be disposed of which means a large amount of wastage
Give four asepsis techniques when dealing with microbes
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
