Food production
- Yoghurts and cheese
- produced by bacterial growth in milk
- this chnages the texture and flavour
- the bacteria prevent the growth of those bacteria that caue spoilage
- this helps preserve ood
- 'Qourn'
- produced by the growth of a fungus 'Fusarium'
- The fungal mass (mycelium) is processed and shaped into food
- Soy Sauce
- Roasted soya beans are fermented with yeast of fungus such as Aspergillus.
Drugs and pharmaceuticals
- Penicillin
- this is a product of the growth of a fungus called Penicillium.
- It is a by-product of the organisms metabolism
- this is isolated from the growth medium and is used as an antibiotic
- Insulin
- Bacteria such a E.coli are genetically modified to carry human insulin gene
- they secrete insulin as they grow
Bioremediation of waste products
- a variety of bacteria and fungi use organic waste in the water as nutrients and make wast harmless
- e.g. Fusarium grown on corn steep liquor, a waste product of the corn milling industry.
Why use bacteria and Fungi?
- grows rapidly in favourable conditions
- can produce chemicals or proteins that are released into the surrounding medium and ce be harvested
- can be genetically modified to produce specific products
- grow well at relatively low temperatures
- can be grown anywhere in the world - not climate dependant
- generated products that are in a pure form than those generated via chemical processes
- can often be grown using nutrient materials that would otherwise useless or even toxic to humans
GROWTH CURVE
What is a culture?
- it's a growth of micro-organisms
- it may be pure culture (single species) or mixed culture (mix of species)
- they can be cultured in liquid broth or solid nutrient agar gel.
Lag phase - organisms adjusting to conditions, cells active but not reproducing. Population is fairly constant
Log phase - population size doubles each generation. plenty of space and nutrients to reproduce.
Stationery phase - nutrients level decrease, waste products builds up. Death rate = production rate
Death phase - nutrients exhaustion, increased level of toxic waste products. Death rate > reproduction rate.
FERMENTATION
- Fermentation refers to the culturing of micoorganisms
- they could grow both aerobically and anaerobically in tanks called fermenters
Fermenters
- growth of an microorganism on an enormous scale
- begins with a 'start culture' a small pure culture from whicl all microorganis will grown
- conditions
- temperature
- type and tie of addition of nutrients
- O2 concentration
- pH
- Batch culture
- microorganisms mixed with specific quantity of nutrients then grown for a fixed period, no further nutrients added
- advantages and disadvantages
- growth rate slower
- easy to set up and maintain
- if contaminated, one batch is lost
- lless efficient - not operating all the time
- useful for producing secondary metabolites
- Continuous culture
- microorganisms mixed with nutrients and nutrients are added continuously with products removed continuously throughout the process
- advantages and disadvantages
- growth rate higher
- difficult to set up and maintain
- if contaminated, huge volumes lost.
- ore efficient, operated continuously
- useful fro primary metabolites.
- Aseptic technique - asepsis
- unwanted micro-organisms can contaminate the fermentation process
- to avoid this, aseptic technique ensures contamination of the culture does not occur
- contamination may result in products being unsafe
- unwanted micro-organisms
- compete with culture micro-organisms for nutrients and space
- reduce the yield of the product
- may cause spoilage, produce toxic chemicals or destroy the culture micro-organisms
Metabolism and metabolites
- Metabolites include:
- chemicals such as hormones and enzymes
- waste products e.g. CO2, urea and O2
- these can be nutrients required by other organisms
- primary metbolites
- these are produced by organisms as part of its normal growth
- amino acids
- proteins
- enzymes
- ethanol
- lactate
- secondary metabolites
- these are produced by the organism and are not part of its normal growth
- antibiotic chemicals
- produced y a small number of microorganisms
Industrial enzymes
- Commercial use of enzymes
- Pectinase can be used in fruit juice extraction
- Metabolic enzymes in the bacteria A. niger produce citric acid used in detergents
- Downstreaming
- isolated enzymes can be produced in large quantities through biotechnology
- their extraction from the fermentation medium is known as downstream processing
- this is their separation and purification
- Immoilising enzymes
- when using enzymes in industry they need to be removed after they have served their purpose
- this can be a costly process
- it is possible to immobilise enzymes and prevent them from mixing
- immbolisation
- this is a technique were enzyme molecules are held, separated from the reaction mixture
- substrate molecules can bind to the enzymes and the products are formed go back into the reaction leaving the enzymes in place
- methods
- adsorption
- covalent bonding
- entrapment
- membrane separation
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