Biotechnology
- Created by: imanilara
- Created on: 10-01-16 15:49
Biotechnology basics
Biotechnology- the industrial use of living organisms to produce food, drugs or other products
Food: Cheese and yoghurt- Lactoballicus, Mycoprotein- Fusarium
Drugs: Penicillin- Penicillium, Insulin-E.coli
Why do we use micro-organisms?
- grow rapidly in favourable conditions- double every 30mins
- produce proteins or chemicals that can be harvested
- genetically engineered to produce specific products
- can grow at low temps, most chem. processes at 400degrees, so 40 is low
- Not dependent on climate-can grow anywhere in the world
- Can be grown using waste nutrient products, e.g. waste paper
The growth curve
Culture- growth of microorganisms, could be a single species (pure) or a mixture of species (mixed). Can be cultured in a liquid e.g. agar.
Standard growth culture models the pop. size of microorganisms in a closed culture. "Closed"=conditions are fixed, where no new materials are added or waste products removed.
PHASE 1: LAG PHASE=
- microorganisms adjusting to conditions
- releasing enzymes for extracellular digestion-break down surrounding nutrient agar,
- cells active but not reproudcing yet-pop=constant.
PHASE 2: Exponential/log phase=
- Cells have broken down and absorbed nutrients
- Lots of nutrients available
- Favourable conditions, little intraspecific competition=pop size doubles each generation-every 20-30mins
The growth curve
PHASE 3- STATIONARY PHASE=
- Nutrients levels decrease
- CO2 builds up
- Some individuals die-death rate=growth rate
- in an open system, this would be called carrying capacity
PHASE 4- DEATH PHASE=
- Nutrients very low
- Waste products=HIGH
- death rate increases
- death rate > growth rate, pop. size decreases
- in closed system, all will eventually die
Phases of Microbial Growth
Metabolites
Metabolite= product of metabolism (all the chemical reactions occuring in an organism)
These include: New cells, waste products, hormones/enzymes
Primary metabolites-
- produced by an organism as part of its normal growth=(amino acids, enzymes, nucleic acids)
- produced in good conditions
- ALL MICROORGANISMS PRODUCE THESE
Secondary metabolies-
- Not produced as part of normal growth
- begins after the main growth period, therefore doesnt match the pop.
- produced in less favourable conditions
- produces mols not essential for growth, but still useful, e.g. penicillium produces penicillin to help it compete w bacteria
- NOT ALL MICROORGANISMS CAN PRODUCE SECONDARY METABOLITES
Fermenters
Fermenters= huge tanks where internal conditions can be controlled
Sensors- detect current conditions and feed this back to output devices to bring conditions back to norm
Temp- too hot=denaturing of enzymes, too cold=rate of growth too slow
Nutrient supply-
timing of adding nutrients determined by whether u are producing secondary or primary metabolites
Must be high in carbon, hydrogen, nitrogen and oxygen
O2 concentration= growth=aerobic resp. bc no oxygen leads to anaerobic conditions=waste products+slow growth rate
pH=affects activity of enzymes, alters 3D shape and breaks hydrogen bonds
Asepsis
ABSENCE OF UNWANTED MICROORGANISMS=ASEPTIC TECHNIQUES
Unwanted microorganisms=contaminants
Contaminants must be kept out so they don't-
- Compete w the microorganisms for space+nutrients
- Reduce the yield of the product
- Spoil the product
- Produce toxic chemicals as metabolites
- Make food/medicine unsafe
Batch and Continuous Culture
Batch=
- starter pop. mixed w a fixed amount of nutrient and allowed to grow for a fixed period w no further nutrient added
- Products collected at the end
- Growth Rate slower-nutrients run out
- Not operating all the time
- Easy to set up and maintain
- Useful for producing secondary metabolites (allows unfavourable conditions to develop)
- Penicillin produced this way
Continuous=
- Nutrients added and waste products removed regularly
- Set up more difficult
- Maintaining conditions difficult
- More efficient as operates continuously
- good for primary metabolites
Immobilised Enzymes
Used because:
Highly specific-catalyse reactions between specific chemicals w Fewer by-products and less purification necessary
Lowers temp- enzymes function well at low temps which are cheaper
However you have to separate the enzyme from the product, and downstream (where enzymes are extracted from the product) is time-consuming and expensive, therefore immobilse them!
Enzymes not present w the product =low downstream costs, enzymes immediately available for reuse=increases continuity, more stable and less likely to have pH or temp damage
Takes more time and equipment=high costs, less active as they don't mix freely w substrate, enzyme leakage can still happen.
Immobilised Enzymes- 4 methods to set up
FIRST METHOD: ADSORPTION
- enzyme molecules mixed with immobilising support and bind to it through hydrophobic reactions and ionic links. Adsorbing agents=glass beads, clay
- Not strong bond-enzyme leakage can happen, but active site is exposed
SECOND METHOD: COVALENT BONDING
- enzymes covalently bonded to insoluble material, e.g. clay, using cross linking agent like sepharose.
- Little leakage and exposed active site--but doesnt immobilise the whole enzyme
THIRD METHOD: ENTRAPMENT
- enzymes trapped within a substance, eg gel bead. Slow rate of reaction as molecules have to get through barrier-active site less accessible
FOURTH METHOD: MEMBRANE SEPARATION
- enzyme separated from substrate using membrane-enzyme too big to pass through it.
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