What is Biotechnology
Biotechnology- all technological processes that make use of living organisms or parts of living organisms, in order to manufacture useful products or provide useful services for human exploitation.
Originaly used to make yoghurt and cheese. Was also used for baking and brewing.
Used currently in many areas of regular daily lives:
Healthcare - produce drugs and used in gene therapy
Agriculture- microprogation of plants, develpoment of GM (genetically modified) plants
Industry- Genetically modifying organisms to produce enzymes
Food science- creating foods with better nutritional value (golden rice) and better taste.
Why use microorganisms
- Grow rapidly in favorable conditions (can be as little as 30 mins)
- Often produce protiens or chemicals that are released into surrounding medium (can then be harvested)
- Can be gentically engineered to produce specific products
- Grow well in low temeperatutures (muchg lower than that of chemical engineering)
- Can be grown anywhere in the world (not dependant on climate)
- Tend to generate products in a more pure form (than that of chemical processing)
- Can often be grown using nurtient materials that would be otherwise usless/ toxic to humans
The standard growth curve (part 1)
- A small number if organisms placed in a fresh 'closed culture' will undergo population growth in a standard way.
- 'Closed culture' - A culture is a growth of microorganisms. Can be a single species (pure culture) or a mixture of species (mixture pulture)
- When population growth occurs the growth cna be plotted on a graph.
- This graph consists of 4 parts :
Decline/ Death phase.
The standard growth curve (part 2)
- Lag phase- the organisms are adjusting to the surrounding conditions. This can involve taking in water, cell expansion, activating specific genes and producing specific enzymes. The cells are active but not reproducing so population stays stale.
- Log phase- the population doubles every generation. This is because every individial has enough space and nutrients. (length of this phase depends on how quickly the organisms use up their rescources)
- Stationary phase- Nutrient levels decrease and waste products build up e.g. carbon dioxide. Indiviudals die at the same rate that new ones are produced.
- Decline/Death phase- Nutrient levels exhausted and waste product build up becomes toxic leading to the death rate raising above the production rate. Eventualy every organism will die
- Metabolism- the sum total of all the chemical reactions that go on in an organism
- Can include processes such as :
new cells and cellular components
Chemcials such as hormones and enzymes
- Primary metabolites- substances produced by an organism as part of its normal growth, e.g. amino acids, protiens, enzymes, nucleic acids. The produciton of these matches the growth in population of the organism.
- Secondary metabolites- are substances produced by an organism that is not part of its normal growth, e.g. antibiotics. The production of these usualy begins after the main growth period and so does no match the growth in populaiton change .
Industrial scale fermenters
- Growing conditions are differant for differant microorganisms, and whether the process is designed to to produce a primary or secondary metabolite.
- Temperature- too hot and the enzyme is denatured, too low reaction is too slow.
- Type and addition of nutrients- microorganisms require a nutrient supply, including carbon and nitrogen.
- Oxygen concentration (O2 conc)- most microorganisms respire in aerobic conditons, enough oxygen must be provided. Lack of oxygen leads to anaerobic respiration, which lowers rate.
- pH- too high/ too low and the enzyme is denatured
- A batch culture is where the starter population is mixed with a specific quantity of nutrient solution, then allowed to only grow for a fixed time with no more nurtient added. At the end the tank is emptied.
- growth rate is slower as nutrient level declines with time
- easy to set up and maintain
- if contamination occurs, you only loose one batch
- less efficient, fermenter is not in operation at all times
- useful in producing secondary metobalites.
- A continuous culture is where nutrients are added to the fermentation tank and the products are removed at regular intervals/ continuously.
- Growth rate is higher as nutrients are added continuously added to the fermentation tank.
- Set up is more difficult, maintinance of growing conditions can be difficult to achieve.
- If contamination occurs, you have lost large volumes
- More efficient, fermenter is on at all times
- Useful for producing primary metabolites.