Biotechnology

 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 

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

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

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= 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

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= 

• 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

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.

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.