6.2.1 Uses of Microorganisms in Biotechnology

Question 1

Brewing

Answer 1

Involves yeast (Saccharomyces carlsbergens/cerevisiae)

1. Malting: barley produces enzymes that convert starch to sugar
2. Kilning: heated to 80°C to kill germinated seeds
3. Mailing: crush dry barley to produce powder (grist)
4. Mashing: mix grist w/ hot water and maintain at 65°C for 1 hour - add hops + antiseptic (wort)
5. Fermentation: add yeast to wort and maintain temp (eventually growth is inhibited)

C6H12O6 → 2 C2H5OH + 2 CO2

6. Finishing: filter and keep for few weeks until ages and becomes pure + clear

Question 2

Baking

Answer 2

Involves yeast as a rising/biological agent, can reproduce rapidly + rise at a faster rate
Does not have flavour

1. Dissolve yeast at 49-54°C and leave initially for 30-60 mins to ferment - produce CO2 bubbles when respire
2. CO2 bubbles expand when baked and alcohol (from anaerobic) produced evaporates away - yeast killed and gluten sets

C6H12O6 + O2 → CO2 + H2O (aerobic)
C6H12O6 → 2 C2H5OH + 2 CO2 (anaerobic)

Question 3

Cheese production

Answer 3

Involves lactobacillus, using pasteurised milk as a raw material
Cheese is used as a good source of fat + calcium, can be preserved for longer

1. Bacteria digest lactose at a temperature of around 30°C to produce lactic acid - lowers the pH of milk
2. proteins in milk denature and curds + whey separate at a temperature of around 20-40°C (at high temps rennet enzyme activity decreases due to precipitation preventing gel forming)
3. Curds are processed to form hard cheeses, and fungi (mould spores from saprotrophic fungi Penicillium glaucum) is introduced (blue cheese etc.)

Question 4

Yoghurt production

Answer 4

Involves Lactobacillus bulgaricus - forms ethanal and streptococcus (forms lactic acid, causes them to coagulate as the proteins denature)

Yoghurt is used as biomed for gastrointestinal issues, improving lactose intolerance
Rich in amino acids, vitamins + minerals (immune system boost)
Source of calcium, potassium + protein)

1. Sterilise equipment and heat milk to around 90°C to kill bacteria
2. Cool the milk to 40°C and use equal amounts of Lactobacillus + Streptococcus, then incubate for 4-5 hours (part of master culture can be used every day for a week)
3. Transfer yoghurt into cartons at 10°C - lasts 19 days (if at 2-3°C)

Question 5

Penicillin production

Answer 5

Involves Penecillin chrysogenum (discovered on a melon) commercially, but P. notatum on original mould

Affects gram positive bacteria as the cell wall is thicker

1. Species of mould from Penicillium genus cultured in industrial fermenters - deep-tank fermentation at 25-27°C
2. Added to medium with glucose, phenoxyacetic acid, corn steep liquor + nitrogen source and oxygen supplied for mixing (pH 5.5-6)
3. Extraction + purification to produce large volumes of drugs for therapeutic use - treat bacterial endocarditis etc.

Question 6

Bioremediation

Answer 6

Involves microorganisms that can neutralise contaminants, break down organic material into CO2 + H20 in soil/water - treat solvents + pesticides

GMO being developed to break down non-typical substances/pollutants

• Natural microorganisms exceed GMO in decontamination
• need suitable temp, pH, water availability etc.

less labour + equipment, can monitor treatment w/ fewer waste products
HOWEVER only treats few products (metals can’t be treated)