Biotechnology

Question 1

What are the four main areas microorganisms are used in biotechnology?

Answer 1

Food
Pharmaceutical drugs
Enzymes
Other products such as biogas, citric acid and bioremediation

Question 2

Examples of microorganisms being used in the food industry

Answer 2

• Ethanol in beer and wine (yeast)
• Carbon dioxide to make bread rise (yeast)
• Lactic acid to make cheese and yoghurt (Lactobacillus bacteria)
• Mycoprotein to make veggie food (fungus)
• Soya - soya beans fermented to make soy sauce (yeast)

Question 3

Examples of microorganisms being used to make pharmaceutical drugs

Answer 3

• Penicillin (penicillium fungus)
• Other antibiotics
• Insulin (genetically modified bacteria)

Question 4

Advantages of using microorganisms in biotechnology

Answer 4

• cheap and easy to grow
• in most cases, process takes place at lower temperatures saving energy and reducing costs
• process can take place at normal atmospheric pressure which is safer
• not dependent on climate
• microorganisms have a short life cycle and reproduce quickly
• microorganisms can be genetically modified relatively easily
• Fewer ethical considerations
• product is often more pure and easier to isolate

Question 5

How are other organisms used in biotechnology?

Answer 5

Genetically modified mammals can be used to produce useful proteins. Some have the protein incorporated into milk which can be easily harvested. Others have it incorporated into their blood.

Question 6

How to make yoghurt

Answer 6

Yoghurt is milk that has undergone fermentation by Lactobacillus bacteria which converts lactose to lactic acid. The acidity denatures the milk protein causing it to coagulate and thicken. Flavours and colours are then added.

Question 7

How to make cheese

Answer 7

• Milk is treated with Lactobacillus to produce lactic acid from lactose
• Once acidified it it mixed with rennetwhich contains the enzyme rennin
• rennin coagulates the milk protein caesin in the presence of calcium ions to produce curd
• curd is separated from the liquid component and pressed into moulds
• production of blue cheese involves the addition of fungi

Question 8

How to bake bread

Answer 8

Yeast makes bread rise.CO2 produced by fermentation of sugars in the dough ensures it doesn’t stay flat. Any alcohol evaporates during the cooking process.

Question 9

Brewing

Answer 9

Yeast is added to a type of grain (e.g barley) which respires anaerobically using glucose from the grain o produce ethanol and CO2. This is called fermentation.

Question 10

Penicillin production

Answer 10

Penicillium fungus grown under stress in industrial fermenters and penicillin is produced and collected. When under stress, penicillin is produced to stop bacteria from growing and competing for resources.

Question 11

Insulin production

Answer 11

Made by genetically modified bacteria which have had the gene for human insulin production inserted into their DNA. Grown in an industrial fermenter and the insulin is collected and purified.

Question 12

Bioremediation

Answer 12

The process of using microorganisms to remove pollutants. Pollutant removing bacteria that occur naturally at a site are provided with extra nutrients and enhanced growing conditions so they can multiply. The bacteria break down the pollutants into less harmful products.

Question 13

Advantages of using microorganisms in food production

Answer 13

• production of protein can be much faster
• very high protein content
• production can be increased/decreased according to demand
• no animal welfare issues
• protein contains no animal fat/cholesterol
• microorganism can be easily modified to adjust the amino acid content
• can go all year round
• not much land required

Question 14

Disadvantages of using microorganisms in food production

Answer 14

• some people may not want to eat fungal protein
• protein needs to be purified to ensure it isn’t contaminated
• microbial biomass can have a lot of nucleic acids which must be removed
• amino acid profile may be different from animal protein
• care must be taken to ensure the culture is not infected with the wing organisms

Question 15

What conditions must be controlled in fermenters?

Answer 15

Temperature - too hot will denature enzymes, too cold and growth will be limited
Nutrients available - sources of carbon, nitrogen, vitamins and minerals are needed
Oxygen availability - for aerobic respiration
pH - will affect enzymes
concentration of product - if product is allowed to build up it may affect the synthesis.

Question 16

What is the water jacket for on a fermenter?

Answer 16

Allows circulation of water around a fermenter to regulate temperature

Question 17

What is batch fermentation?

Answer 17

Where microorganisms are grown in individual batches in a fermentation vessel. Products made only when cells are placed under stress such as high population density or limited nutrients availability. These are secondary metabolites and are produced in the stationary phase of growth.

Question 18

What is continuous fermentation?

Answer 18

Microorganisms are continually grown in a fermentation vessel without stopping. Nutrients are put in and products taken out at a constant rate. These are primary metabolites.

Question 19

Why is asepsis important?

Answer 19

Unwanted miroorganisms will:

• compete with the cultured microorganisms for nutrients and space
• reduce the yield of useful products
• spoil the product
• may produce toxic chemicals

Question 20

Advantages of bioremediation

Answer 20

• uses natural systems
• less labour/equipment required
• treatment in situ
• few waste products

Question 21

Aseptic techniques

Answer 21

• wash hands
• disinfect working area
• have bunsen burner operating nearby to prevent microorganisms settling
• when opening a vessel, pass neck of bottle over flame to prevent bacteria entering
• do not lift lid off completely
• equipment should be passed through flame before and after contact with microorganism

Question 22

Sterilisation

Answer 22

Medium sterilised by heating in an autoclave which kills all living organisms. Then poured into sterile petri dishes.

Question 23

Inoculation

Answer 23

The introduction of microorganisms to a sterile medium by:

• streaking, wire loop used to transfer liquid medium by dragging it across the surface
• seeding, sterile pipette used to transfer small drop of liquid medium to the surface
• spreading, glass spreader may spread inoculated drop across surface

Question 24

Incubation

Answer 24

Petri dish taped up and placed in a warm environment such as an incubator.

Question 25

What is a closed culture?

Answer 25

When growth takes place in a vessel that is isoltaed from the external environment. Extra nutrients aren’t added and waste products aren’t removed from the vessel during growth.

Question 26

What is the lag phase of the growth curve?

Answer 26

Population does not grown quickly because the population is still small and the organisms are adjusting to their new environment. The microorganisms have to make enzymes and other molecules before they can reproduce.

Question 27

What is the exponential phase of the growth curve?

Answer 27

Population size increases quickly because conditions are at their most favourable for reproduction (lots of food and little competition).

Question 28

What is the stationary phase of the growth curve?

Answer 28

The population size stays level because the death rate of the microorganisms is equal to the reproductive rate. They start to die because nutrients get used up and toxic waste products build up.

Question 29

What is the decline phase of the growth curve?

Answer 29

Population size falls because death rate is larger than reproductive rate. Food is very scarce and waste products are at toxic levels.

Question 30

When are primary metabolites collected?

Answer 30

Log phase

Question 31

When are secondary metabolites collected?

Answer 31

Stationary phase

Question 32

What is an immobilised enzyme?

Answer 32

An enzyme that is held in place and not free to diffuse through the solution

Question 33

Advantages of immobilised enzymes

Answer 33

• enzymes don’t mix with the desired product so extraction costs are lower
• enzymes can be easily reused
• continuous process made easier as there are no cells requiring nutrients and releasing waste products
• immobilised matrix protects the enzyme from extreme conditions

Question 34

How to immobilise enzymes

Answer 34

ADSORPTION - enzymes bound to a supporting surface by hydrophobic interactions and ionic links. Bonding forces not always strong and enzyme may leak into reaction mixture.
COVALENT BONDING - bonded to supporting surface by covalent bonds using a cross linking agent. Less likely to leak into reaction mixture but more expensive.
ENTRAPMENT - enzymes trapped in a matrix so they can’t move. Substrate must be small enough to be able to diffuse into the entrapment mixture
MEMBRANE SEPARATION - separated from reaction mixture by a partially permeable membrane. Substrate must be small enough to pass through the membrane.

Question 35

Disadvantages of using immobilised enzymes

Answer 35

• extra equipment can be expensive
• immobilised enzymes are more expensive to buy than free enzymes
• immobilisation of enzymes may lead to reduction in their activity

Question 36

Uses of immobilised enzymes in industry (5)

Answer 36

• conversion of lactose to glucose and galactose to produce lactose free dairy products
• production of semi-synthetic penicillins which are effective against penicillin resistant organisms. The immobilised enzyme penicillin acylase is used.
• conversion of glucose to fructose by the enzyme glucose isomerase. Fructose is sweeter so is used as a sweetener in food.
• glucoamylase is used for the production of dextrins in carbohydrates to glucose
• aminoacylase produces pure samples of L-amino acids which is the isomer that can be used in the body