Biotechnology 6.2.1 Flashcards
why are microorganisms used in biotechnology?
- cheap
- short life cycle
- rapid growth rate
- simple nutrient requirement
- relatively low temp
also. .
- no welfare issues
- enormous range of microorganisms which can carry out many functions
- GM allows manipulation of microorganisms to carry out unnatural reactions eg. producing human insulin
- raw materials cheap
bioremediation
use of biological systems (usually microorganisms) to remove soil and water pollution eg. after oil spill
Brewing
microorganism used
process described
Yeast
- respires aerobically, making ethanol
- yeast is added to a grain eg. barley
- batch culture
Cheese making
microorganism used
process described
Bacteria
- feed on lactose in milk (change texture & taste, and inbihits the growth of bacteria which make milk go off)
- pasteurise milk (heat to 95C) and homogenise (fat droplets are evenly distributed)
- mix w bacterial cultures, and chymosin enzyme, which clots the milk
- milk separates into solid curds and liquid whey
- cook & strain
- put in drums and left to mature & ripen as bacteria continue to act
- batch culture
Yoghurt production
microorganism used
process described
Bacteria
- Lactobacillus bulgaricus (forms ethanal)
- Streptococcus thermophilus (forms lactic acid)
- mixture is pasteurised, homogenised, & cooled
- milk mixed w two types of bacteria & incubated
- flavours can be added
- batch culture
Penicillin production
what makes penicillin?
how is it grown commercially?
- Fungus (Penicillium chrysogenum) produces the antibiotic penicillin which stops bacteria from growing
- grown under stress in industrial fermenters (batch), collected and processed
Insulin production
GM bacteria have the gene for human insulin production inserted into their DNA
- grown in an industrial fermenter (continuous culture)
- insulin is collected and purified
advantages of using microorganisms to make food for human consumption
+ grow fast
+ short life cycle
+ cheap
+ simple growth requirements
+can be grown on waste products
+ less land is req. than w/ agriculture
+ can be cultured in any climate or season
+ any country (can be used in LEDCs for malnutrition)
+ single-cell protein can be healthy alternative to meat
+ no welfare issues
disadvantages of using microorganisms to make food for human consumption
- must maintain aseptic conditions so that other microorganisms do not grow & contaminate food
- people may not like the idea of eating food grown from waste products
- single-cell protein doesn’t have the same flavour or texture as meat
- the fungus used to make Quorn is hight in nucleic acids, which are metabolised to uric acid in the body. This can cause gout.
how to culture microorganisms in the lab
- use sterile petri dish with agar jelly
- transfer microorganisms from sample to the plate using a sterile wire inoculation loop
- incubate the plates to allow the microorganisms to grow
- nutrients added to the agar to improve growing conditions
what type of fermentation is used when growing Quorn from a fungus?
continuous fermentation
Batch fermentation
Batch fermentation
- closed culture.
- microorganisms grown in discrete batches in an industrial fermenter.
\+ produces secondary metabolites \+ easy to control conditions \+ contamination only affects one batch - large vessels needed - waste builds up - less productive as exponential phase is short
Continuous fermentation
Continuous fermentation
- open culture.
- microorganisms are grown continuously
- nutrients are put in and waste products are taken out at a constant rate
+ greater productivity as organisms are kept in the exponential phase
+ no need to empty and sterilise the fermenter
- difficult to control conditions
- no secondary metabolites produced
- large quantity can be spoiled if contaminated
Continuous fermentation
Continuous fermentation
- open culture.
- microorganisms are grown continuously
- nutrients are put in and waste products are taken out at a constant rate
+ greater productivity as organisms are kept in the exponential phase
+ no need to empty and sterilise the fermenter
- difficult to control conditions
- no secondary metabolites produced
- large quantity can be spoiled if contaminated
aseptic techniques when culturing microorganisms
- work near bunsen as hot air carries microorganisms in the air up
- disinfect work surfaces
- sterilise instruments (wire inoculation loop) by passing through flame to kill microorganisms
- pass neck of bottle through flame after opening and before closing to prevent microorganisms falling in
- minimise time agar plate is open and seal lid as fast as possible
- sterilise glassware in autoclave machine (steam at high pressure)
describe the stages of a standard growth curve for the growth of microorganisms in a closed culture
Lag phase
- pop size slowly increases
- microorganisms have to absorb nutrients, make enzymes etc before they can reproduce
Exponential phase
- pop size increases quickly as the culture conditions are the most favourable for reproduction (lots of food and little competition)
- reproduction rate is v fast (exponential)
Stationary phase
- pop stays level as the death rate = reproductive rate
- microorganisms start to die as not enough food and toxic waste builds up
Decline phase
- pop falls as death rate > reproduction rate
- food v scarce
- lots of toxic waste products
what 5 factors need to be regulated in a fermentation vessel to maximise yield of microorganisms?
- pH
- temp
- nutrient access
- vol of O2
- sterility
how is pH regulated in a fermentation vessel?
pH probe
how is temperature regulated in a fermentation vessel?
water jacket
how is nutrient access regulated in a fermentation vessel?
paddles constantly circulate fresh nutrient medium around the vessel
how is vol of O2 regulated in a fermentation vessel?
sterile air pumped into vessel as needed for aerobic resp
how is sterility regulated in a fermentation vessel?
the vessel is superheated with steam after each use to kill all microorganisms
what formula is used to calculate the no. individual organisms at any given time in a fermentor (batch)
N = N₀ x 2ⁿ
where
N - no. individuals
N₀ - no. initial individuals
n - no. generations
how to conduct an investigation into the factors affecting the growth of microorganisms in the lab
eg. temp
- add same vol of sample to several agar plates
- spread broth across surface of agar using sterile wire inoculation loop
- put lids on the plates and tape shut
- incubate at diff temps upside down to prevent condensation dropping onto the agar
- use a control (uncultured plate)
- leave for same amount of time (24h)
- count no. colonies on each plate
what are the 3 ways enzymes can be immobilised?
- encapsulated in jelly-like beads which act as a semi-permeable membrane
- trapped in silica gel matrix
- covalently bonded to cellulose/collagen fibres
advantages of using immobilised enzymes
+ columns can be washed and reused, reducing cost
+ product doesn’t need to be separated from enzymes, reducing time and cost
+ immobilised enzymes are more stable than free enzymes - less likely to denature at high temps or pH
disadvantages of using immobilised enzymes
- extra equipment required which is expensive to buy
- immobilised enzymes are more expensive to buy outright
- enzyme activity may be reduced as the enzyme can’t freely mix with its substrate
what does glucose isomerase do
converts glucose → fructose
which can be used as a sweetener as it is sweeter than glucose
what does penicillin acylase do
forms semi- synthetic penicillins, which are effective on penicillin resistant organisms
what does lactase do
hydrolysis of lactose
lactose → glucose + galactose
to produce lactose-free milk for lactose intolerant people
what does aminoacylase do
production of pure samples of L-amino acids
amino acids have 2 isomers (L&D) but only L a.as are made naturally and can be used in the body. Aminoacylase can be used to convert chemically synthesised a.as to L a.as
what does glucoamylase do
converts dextrins from starch into glucose
glucose is then used to sweeten/thicken foods
biotechnology
industrial use of living organisms (or parts of living organisms) to produce food, drugs or other product.
