Using Micro-organisms Flashcards
What are the different types of micro-organisms?
Bacteria Fungi Virus Protozoa (e.g. Amoeba) Algae
What are micro-organisms used for?
Medicines (e.g. Penicillin) Food Production Chemicals such as enzymes and fuels Genetic Modification Selective Breeding
What is fermentation?
The chemical breakdown of a substance by micro-organisms like yeast and bacteria, typically involving effervescence and giving off heat.
How do micro-organisms obtain energy? What occurs as this is happening?
Many micro-organisms use an external food source from their growth culture medium to obtain energy. In doing so, they change substances in the medium and are useful.
What is biotechnology?
The use of micro-organisms is make products useful for humans called biotechnology.
Give examples of the roles of micro-organisms in food production.
- Yeast, a fungus, is used to make beer, wine and bread
- Lactobacillus, a bacterium, helps to make yoghurt and cheese
- Acetobacter, a bacterium, converts ethanol in wine to vinegar
What is used to produce/use micro-organisms on a large scale?
An industrial fermenter
What is the role of the steam inlet in the industrial fermenter?
It lets hot steam enter the fermenter, cleaning and sterilising the insides. It removes chemical residue and kills any unwanted micro-organisms.
What is the role of the nutrient inlet in the industrial fermenter?
Allows nutrients needed by the micro-organisms to enter the start and occasionally during the process.
What is the role of the air inlet in the industrial fermenter?
Oxygen is required if a micro-organism respires aerobically. The air is pushed in with pressure and a filter is attached to sterilise air. The inlet is attached to a disk with holes (a spargar) that allows air to enter with pressure and helps mixing air with the contents of the fermenter.
What is the role of the acid/alkali inlet in the industrial fermenter?
To adjust the pH contents, a buffer can be introduced through the inlet.
What is the role of the cold water inlet in the industrial fermenter?
Lets cool water enter the cool water jacket.
What is the role of the cold water jacket in the industrial fermenter?
The fermenter is surrounded by a metal jacket that carries cold water to adjust the temperature of the fermenter. The water circulates in the jacket so that the contents lose heat, and warm water is taken out through another outlet.
What is the role of the water outlet in the industrial fermenter?
Warm water leaves through this outlet.
What is the role of the harvesting outlet in the industrial fermenter?
Once the products are formed, they exit through this outlet for further processing.
What is the role of the exhaust/gas outlet in the industrial fermenter?
Removes excess gas produced during fermentation to avoid pressure build up.
What is the role of the steam outlet in the industrial fermenter?
Releases steam after sterilisation.
What is the role of stirring paddles in the industrial fermenter?
Mix up the contents, keeps micro-organisms in suspension in liquid - essentially ensuring exposure to nutrients and an even temperature throughout.
What is the role of the probes in the industrial fermenter?
They monitor conditions such as pH and temperature. Information is sent to computer control systems and the environment is adjusted accordingly.
What does beer-making involve?
Involves alcoholic fermentation by yeast.
Describe the role of yeast in the production of beer.
Yeast can respire and break down glucose in the absence of oxygen to produce ethanol and carbon dioxide.
What is beer made from?
Beer is made from barley seeds which contain starch, not sugar.
What needs to happen to starch before it is fermented?
It needs to be broken down to sugars because the enzymes needed for this are produced by germinating barley seeds.
Step 1 of Beer Production
Barley seeds are soaked so that they germinate.
Step 2 of Beer Production
Seeds were killed without destroying the enzymes and dried to make malt.
Step 3 of Beer Production
Malt is ground up and mixed with water in a mash tun. Here amylase breaks down starch to maltose.
Step 4 of Beer Production
Mash is boiled to kill the enzymes and then filtered.
Step 5 of Beer Production
Hops are added to give the beer a bit of flavour and stop bacteria from growing.
Step 6 of Beer Production
Yeast is added to ferment the sugars.
Step 7 of Beer Production
When fermentation is finished, beer is centrifuged, filtered and sometimes pasteurised.
Step 8 of Beer Production
It is collected into tasks or barrels.
What are hops?
These add flavour to beer and are a major part of the process.
Definition of centrifuged.
Centrifugation is a process which involves the application of the centrifugal force for the sedimentation of the heterogeneous mixtures with a centrifuges and is used in industrial and laboratory settings.
What is penicillin?
Penicillin is an antibiotic produced by the fermentation of the bacterium penicillium.
What is used to carry out the production of penicillin?
An industrial fermenter
Step 1 of Penicillin Production
Make a broth of spores of the mould penicillium separately.
Step 2 of Penicillin Production
A culture solution containing sugar and other nutrients like ‘corn steep liquid’ are added to the fermenter.
Step 3 of Penicillin Production
Oxygen supplied for the mould to respire.
Step 4 of Penicillin Production
The stirring paddles are used to distribute the contents uniformly.
Step 5 of Penicillin Production
The broth containing spores of the fungus is now introduced and the temperature of the fermenter is kept steady at 24 degrees Celsius.
Step 6 of Penicillin Production
The spores develop into filaments of cells which multiply rapidly, doubling the mass every six hours.
Step 7 of Penicillin Production
After about forty hours, the cells begin to produce penicillin and continue to produce it for several days.
Step 8 of Penicillin Production
Penicillin is secreted out of the cells.
Step 9 of Penicillin Production
The brith is filtered to remove the cells.
Step 10 of Penicillin Production
Penicillin is extracted by organic solvents.
Step 11 of Penicillin Production
It is re-dissolved back into water and made to crystallise to get pure penicillin.
How is yoghurt made?
It is made by solidifying milk proteins by denaturing them. Once the milk proteins are denatured, they turn to semi-solid yoghurt.
What does yoghurt-making depend on?
Fermentation by bacteria.
What are the two types of bacteria commonly used in yoghurt making?
Lactobacillus and streptococcus - both convert lactose into lactic acid.
Step 1 of Yoghurt Production
Milk is pasteurised at 85 to 95 degrees Celsius for fifteen to thirty minutes in order to remove or destroy any pre-existing and unwanted micro-organisms.
Step 2 of Yoghurt Production
It is homogenised for uniform distribution of fat globules.
Step 3 of Yoghurt Production
Milk is cooled to 40 to 45 degrees Celsius. This is done to obtain an optimum temperature for the bacterial enzymes to work.
Step 4 of Yoghurt Production
Milk is inoculated with a starter culture of lactic acid bacteria
Step 5 of Yoghurt Production
Mixture is incubated at this temperature for several hours.
Step 6 of Yoghurt Production
PH falls to about 4.4 which causes the milk proteins to coagulate.
Step 7 of Yoghurt Production
Thickened yoghurt is then stirred and cooled to about 5 degrees Celsius. This ensures enzymatic activity by bacteria.
Step 8 of Yoghurt Production
Flavourings, colourants and fruits may be added before packaging.
Describe the process of bread-making.
Bread is made by mixing different types of flour with yeast. After mixing, it is placed in a warm area and covered with a lid. Yeast breaks down the sugar in the flour by anaerobic respiration, producing ethanol and carbon dioxide. When the bread dough is placed in the oven at high temperature, the ethanol evaporates and carbon dioxide bubbles out. This makes it easier for the bread to rise.
Describe the process of cheese-making.
To make cheese, first yoghurt is made by using different bacterial cultures. The yoghurt is then converted into cheese by the fermentation of fungi. A large variety of cheese can be obtained by using different cultures of fungi.
