22.4 Microorganisms & Biotechnology

Question 1

What is bioremediation?

Answer 1

Use of microorganisms

in breakdown of pollutants & contaminants

in soil/water

Question 2

What is biotechnology?

Answer 2

application of biological organisms or enzymes

in manufacturing processes

Question 3

What are the advantages of using microorganisms in biotechnological processes?

Answer 3

• no/few ethical concerns
• proliferate quickly
• easy to manipulate
• provide own catalysts in form of enzymes, ∴ is cheaper than non-biological industrial processes
• nutrients requirements are often simple & cheap

Question 4

What are indirect-food-making processes? Name examples:

Answer 4

foods which are made from indirect actions of microorganisms

e.g brewing, baking, cheese-making, yoghurt-making

Question 5

How does baking occur?

Answer 5

1. Active yeast mixture + ingredients & left in warm environment to rise
2. Dough has excess air removed, kneaded & left to rise
3. Cooking: CO₂ bubbles expand, causing bread to rise. Yeast cells killed.

Question 6

What is the microorganism involved in baking & what is its purpose?

Answer 6

Yeast

mixed with water + sugar to respire aerobically

releases CO₂ which causes bread to rise

Question 7

How does brewing occur?

Answer 7

1. MALTING
   
   1. barley germinates, produces enzymes which break starch ⟶ sugars for yeast
2. MASHING
   
   1. Malt + warm water.
   2. Enzymes break down starch ⟶ wort
3. FERMENTATION
   
   1. Wort inoculated with yeast
   2. Fermentation (anaerobic respiration) occurs
   3. Eventually yeast dies out due to falling pH, ethanol buildup & lack of O₂
4. MATURATION
   
   1. conditioned for 1 month at 2-6°C
5. filtered, pasteurised & bottled with CO₂

Question 8

What is the microorganism used in brewing & what is its purpose?

Answer 8

Yeast

anaerobic respiration releases ethanol

Question 9

How is cheese made?

Answer 9

1. PASTEURISED & HOMOGENISED
   
   1. Pasteurisation - heated to 95°C to kill bacteria
   2. Homogenisation - fat droplets evenly distributed
2. FORMATION OF CURDS & WHEY
   
   1. Mixed with bacterial cultures
   2. Milk separates into solid curds & liquid whey
3. Curds are cut, cooked in whey, & strained. Whey used for animal feeds.
4. Curds pressed using steel/wooden drums.
5. Left to dry & mature.

Question 10

What is the purpose of using bacteria in cheese-making?

Answer 10

bacteria metabolise lactose in milk

changes texture & taste

also inhibit bacteria which cause milk to go off

Question 11

How is yoghurt made?

Answer 11

1. Skimmed milk powder + milk
2. Pasteurise & homogenise mixture, cool to 47°C
3. Mixed with 1:1 ratio of 2 different microorganisms, incubated.
4. End of fermentation, put into pots.

Question 12

What are the advantages & disadvantages of using microorganisms to produce human food?

Answer 12

• ADVANTAGES
  
  • proliferate quickly, produce protein faster than animals/plants
  • microorganisms have high protein with little fat
  • can use variety of waste materials, reducing costs
  • easily genetically modified
  • not dependent on weather or breeding cycles
  • few ethical issues
  • can be made to taste like anything
• DISADVANTAGES
  
  • can produce toxins if conditions deviate from optimum
  • require separation from nutrient broth & processing
  • require sterile conditions
  • involve GM organisms, which people concern over
  • protein requires purification
  • people dislike eating microorganisms grown on waste
  • requires additives due to little natural flavour

Question 13

What is SCP single-cell protein?

Answer 13

type of protein made for consumption

produced directly by microorganisms