Biotechnology

Topics are:

  1. Living Factories
  2. Problems with Profit and Waste
  3. Reprogramming Microbes

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Biotechnology – the application of biological processes in industry.

Biotechnology is at the heart of a scientific revolution whose impact on every day life may rival that of the microelectronics industry. Though many people may at the moment be familiar only with the products of the traditional biotechnological processes – bread, alcohol, cheese, yoghurt, etc – there is increased use in the home of biological detergents and antibiotics, and look forward to an imminent increase in the world’s use of biotechnologically produced fuels and chemicals for health care products.

Traditional uses of Biotechnology

People have traditionally made use of a wide range of products from plants and animals.

Bread:

  • Yeast make bubbles of CO2.
  • the bubbles in the bread expand on heating to make the bread rise.

Alcoholic drinks:

  • Yeast turns the sugars produced during the malting of grain to alcohol. This process is called fermentation.

Yoghurt:

  • Bacteria ferment the lactose (milk sugar) into lactic acid.
  • This thickens (curdles) the milk.
  • Lactic acid also gives yoghurt its characteristic flavour.

Cheese:

  • Bacteria produce lactic acid to make the milk curdle at the start of the process.
  • Bacteria (for strong cheese) and fungi (for blue cheese) produce chemicals to give flavour.

Yeast:

  • A single-celled fungus.
  • Can use sugar as food.
  • It produces alcohol and CO2 during anaerobic respiration (does not require oxygen).

    Sugar CO2 + alcohol + waste heat energy.

  • This process is called fermentation.

Commercial brewers and distillers control the conditions for the yeast carefully:

  • Temperature – by cooling the vats with water jackets.
  • Cleanliness – before each batch is produced the vats are stream cleaned to kill bacteria.
  • Supply of malted barley for food – the barley is malted to turn the starch in the grains to maltose sugar.

The process is a batch process:

  • In a batch process the manufacturer takes the raw materials and produces the product in a single process.  Then begins again.
  • A batch of barley is:
    • Malted.
    • The barley is germinated.
    • The starch in the grain turns to maltose sugar.
    • It is then fermented using yeast.
    • It may be distilled then bottled.
    • The fermenter vessel must be cleaned before the next batch is started.

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Problems and Profit with Waste

Whenever humans dispose of waste, we risk causing problems to ourselves and to our environment.  From another point of view, simply to dispose of waste may be to neglect valuable resources.

Sewage

Sewage is a rich source of organic and inorganic materials e.g.:

  • Paper.
  • Faeces.
  • Urine.
  • Detergents.
  • Bleaches.
  • Intestinal bacteria.

When sewage is dumped into rivers:

  • Microorganisms use the materials for food.
  • They increase dramatically in numbers by asexual reproduction.
  • They use up the oxygen in the water.
  • Their waste changes the pH of the water.
  • Organisms that require oxygen are killed e.g.:
    • Fish.
    • Small invertebrates.
    • Crustaceans.
  • There is a rise in organisms that can survive an anaerobic environment e.g.:
    • Sludge worms.
    • Blood worms.
    • Rat tailed maggots.
  • Further downstream the bacteria use up the food source and the river reverts to its normal state.

Several diseases are transmitted by drinking water polluted by untreated sewage:

  • Cholera.
  • Dysentery.
  • Typhoid.

Sewage is treated at treatment plants to avoid polluting the environment and causing diseases.

  • Aerobic conditions are needed throughout so that there is complete breakdown of the sewage into CO2 and water by aerobic respiration.

Handling Microorganisms.

Sterile procedure is important when working with microorganisms:

  • To protect the user from possible disease causing organisms.
  • To ensure that only the required organisms get into the culture you are making.
    • Glass equipment and agar media are autoclaved before staring.
      • an autoclave is a large pressure cooker which heats equipment to 121°C using steam.
    • A clean lab coat is worn.
    • Long hair is covered or tied back.
    • The work area is sterilised with disinfectant or methylated spirits.
    • Metal and glass equipment is flamed before and after use.
    • Hands are cleaned with antiseptic soap before and after the procedure.

The Carbon Cycle

Much of the world’s carbon is combined in rocks:

  • This means that carbon is in short supply.
  • In nature it must be recycled.
  • Bacteria and fungi are needed in the carbon cycle in nature.

The microorganisms involved in rotting use the organic material in the dead organism as a source of food for their own respiration.  This releases carbon back into the air as Carbon dioxide.

  • A wide range of organisms is needed to break down the wide range of materials in a dead animal or plant.
  • These are called saprophytic organisms or saprophytes

The nitrogen cycle

Nitrogen in the air is a very unreactive gas.

  • In nature plants in particular need nitrogen in the form of nitrates to make protein.
  • animals can then digest this plant protein to make animal protein for their own growth.
  • Nitrogen gas is very inert, it does not easily combine with other chemicals:
    • Therefore nitrogen must be recycled.
  • Bacteria are needed in the nitrogen cycle in nature:
    • Only bacteria have the necessary enzymes to convert nitrogen gas into nitrates.

Upgrading Waste

Microorganisms can be used to upgrade waste into useful products

  • Less waste is added to the environment
  • Upgrading waste is often cheaper than making the product from raw materials
  • The energy available from the waste increases
  • Bacteria and fungi are used in these processes
  • For example
    • The sludge from sewage can be fermented with bacteria to produce methane gas for heating systems and generators.
    • Molasses from sugar cane refining can be used to make vinegar
    • Waste starch from crisp making can be used to make mycoprotein (quorn) a rich source of protein.
    • Waste straw and horse manure can be used to grow mushrooms.
    • Whey from cheese making can be used for fungal respiration to make cattle feed (another rich source of protein).
    • Fermentation (the process of obtaining a useful product from the anaerobic respiration of microorganisms) can be used to make useful fuel.
    • Sugar is fermented to make alcohol
    • Motor vehicles can be converted to run on this rather than petrol (gasohol)
      • This fuel is a renewable resource unlike petrol and diesel
      • The waste from burning this fuel is much less harmful to the environment containing only CO2 and water.

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Reprogramming Microbes

Much of the thrust of modern biotechnology comes from man’s ability to manipulate the essential life processes of organisms.

Genetic Engineering

Genetic engineering has became an important process in the latter part of the 20th century

  • In genetic engineering genes from one species of organism are transferred to the chromosomes of another organism to cause it to make a useful product.
  • The normal control of bacterial activity depends on its chromosomes.
  • Manipulation of chromosomal material can cause bacteria to change the way they behave and the products they make. Enzymes obtained from viruses are used to cut and paste genes from one organism into another.

This has many advantages:

  • It is less expensive than traditional methods.
  • The chemical coded for by the gene is produced in very large quantities.
  • The chemical is very pure. The process is much faster than traditional methods.
  • Some products produced this way are:
    • Human insulin.
    • Human factor VIII (needed for blood clotting).
    • Interferon (an anti-viral drug).
    • Human Growth Hormone.
    • Enzymes in washing powders:
      • Since many stains on clothes are biological in origin enzymes clean them effectively’
      • These enzymes clean at low temperatures saving energy.
      • These are produced by genetically engineered bacteria.

Genetic engineering can be used to move genes between species that would not normally be able to interbreed.

  • Traditional animal and plant breeding techniques can’t do this
  • Useful genes for resistance to disease can be transferred between crops
  • Useful genes can be transferred to domestic animals e.g.:
    • Resistance to disease can be transferred from tobacco to tomatoes.

Antibiotics

An antibiotic is a chemical that prevents growth of bacteria.

  • Some bacteria are resistant to some antibiotics.
    • e.g. TB bacteria can only be treated with streptomycin.
  • More disease bacteris gain resistance each year (superbugs).
    • It is important to take all the antibiotics in a course from your doctor to help prevent this.
  • We need a range of antibiotics to ensure that all species of bacteria can be killed.
  • A multidisc can be used to test which antibiotic kills a particular bacterium.
 

Immobilising Enzymes

Enzymes can be immobilised in gel pellets or more usually on the surface of glass beads:

  • By passing substrates (raw materials) over the immobilised enzymes a product can be obtained at the end of the fermenter vessel.
  • This is a continuous process (compare to the batch process for making alcohol)
  • Very large quantities of product are produced quickly and cheaply in a continuous process.
  • There is no need to separate the product from the enzyme that produced it.
  • The enzyme (which is probably expensive) gets used for a long time and is not lost in the process.
  • There is no need for frequent cleaning of the fermenter vessel as in a batch process.

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