In 1928 Alexander Fleming left some culturing bacteria on an open window there were clear spots of agar that had stopped the bacteria from growing. Fleming found that the microorganism that had invaded the Petri dish was a common mould called Penicillium Notatum. He extracted a tiny amount and treated a wound with it. It was difficult to extract and would not be able to harvest enough for it to be useful. During the Second World War Howard Florey and Ernst Chain tried desperately to find an antibacterial drug. They turned to Flemings mould and trialed it to see that it worked. It was successful but they could not harvest enough of it for it to be useful. After a mould growing on a melon was found to yield 200 times more penicillin than Flemings mould, they found it grew easily in deep tanks. By 1945, they were producing enough to treat 7 million people a year.
Modern Penicillin Production
Nowadays, we grow the mould in a sterilized medium. The medium is ‘Corn Steep Liquor’, which contains sugars, amino acids, mineral salts and other nutrients. We use huge 10 000 litre Fermenters which have strong paddles to stir the broth. The penicillin mould needs lots of Oxygen to survive. All the nutrients have to be used up before the mould stars to make penicillin. This means a lag period at the start of production when the mould use up the nutrients.
Biogas is a flammable mixture of gases formed when bacteria break down plant material or the waste products of animals in aerobic conditions. It is mainly Methane but the composition varies, because it depends on what is put into the generator and which bacteria are present.
When it comes to I/GCSE Biology, millions of tones of faeces and urine are made by animals like cows, sheep, pigs and humans. Also, in many places, plant material grows very rapidly. Both the plant material and the animal waste contain carbohydrates. They make up a potentially huge energy resource.
The bacteria in biogas production work best at about 30 degrees Celsius. This means biogas generators work best in hot countries. However the process generates heat (The reactions are Exothermic). This means that if the biogas generators are provided with heat to start with, and are well insulated, they can work anywhere. You can also use the waste from the generators as a fertiliser. What you put into a small generator has a big effect on what comes out. Many different organisms are involved ub the breakdown of material in biogas production.
Carbon Dioxide- 15%- 45%
Hydrogen Sulfide- 0%-3%
In tropical countries plants grow fast. Sugar can has a juice which is very high in carbohydrates, particularly Sucrose. We can break the starch in maize kernels down into Glucose using the enzyme Carbohydrase.
Ethanol Based Fuels
Refer to I/GCSE Biology, if sugar rich products from cane and maize are fermented Anaerobically with yeast, the sugars are broken down to give ethanol and water. This ethanol can be used as fuel in a car.
Advantages of Ethanol:
- Does not produce toxic gases
- Can be mixed with petrol to produce Gasohol
- Is Carbon Neutral- produces no overall increase in CO2 levels
Disadvantages of Ethanol
- Requires lots of plant material to produce ethanol
- Needs research to be sustainable on a large scale
You got it now!