Microorganisms and biotechnology

• Biotechnology involves applying biological organisms or enzymes to the synthesis, breakdown or transformation of materials in the service of people
• Most commonly used organisms in biotechnology are fungi, particularly yeasts, and bacteria which are more useful in the newer technologies

The use of microorganisms

• Most biotechnologies involve enzymes in a manufacturing process and the most stable, convenient and effective form of the enzymes is a whole microorganism
• Used because:
  • No welfare issues to consider - only need optimum conditions for growth
  • Enormous range of them which are capable of carrying out reactions that can be used
  • Can be genetically engineered to carry out reactions they wouldn't naturally
  • Short life cycle and rapid growth rate
  • Nutrient requirements are often cheap and simple
  • All they need is an oxygen supply, relatively low temperatures and food and bring their own enzymes so the processes are kept cheap

Indirect food production

• If the conditions aren't ideal the microorganisms don't grow properly and they don't work as effectively
• Conditions that are ideal for helpful microorganisms may also be ideal for the food to spoil or pathogens to grow so it has to be sterile
• Some people have ethical issues with the use of GM organisms
• Baking
  • Yeast + sugar + water to respire aerobically
  • Carbon dioxide produced makes the bread rise
  • Yeast cells are killed during cooking
• Brewing
  • Yeast respires anaerobically to make ethanol
  • GM yeasts ferment at lower temperatures to make the process cheaper
• Cheese-making
  • Bacteria are used
  • They feed on the lactose in milk to change the texture and taste
  • Inhibiting the growth of the bacteria stops the milk going off
• Yoghurt-making
  • Bacteria are used
  • Often Lactobacillus bulgaricus forms ethanal and Streptococcus thermophilus forms lactic acid
  • Both produce extracellular polymers that give the yoghurt its smooth, thick texture

Direct food production

• Facing protein shortages, scientists have developed ways to use microorganisms to directly produce edible proteins
• ^^ is single-cell protein (SCP)
• Most commonly known one is Quorn
• ^ single-celled fungus that is grown in large fermenters with glucose syrup
• They are combined with albumen then compressed and formed into meat substitututes
• High in protein and low in fat
• Yeasts, algae and bacteria can be used to grow proteins that match animal proteins as well as plant proteins 
• ^^ can be grown on almost anything, are cheap and low in fat but people have reservations about food grown on waste
• SCP are used more to feed animals that we prefer to eat like cattle and pigs

Advantages of using microorganisms to produce human food

• Produce proteins faster than plants or animals
• Have a higher protein content and lower fat content
• They use a range of waste materials which reduces the cost
• Can be genetically modified easily
• Not dependent on weather or mating cycles
• No welfare issues
• Can be made to taste like anything

Disadvantages of using microorganisms to produce human food

• Some microorganisms can also produce toxins if the conditions aren't optimum
• Have to be separated from the nutrient broth and processed to make the food
• Need sterile conditions which adds to the cost
• Many people have concerns over eating GM foods
• The protein has to be purified to make sure its not contaminated
• People dislike the idea of eating food made on waste
• Has little natural flavour - have to add additives