ADVERTISEMENTS:
Here is a term paper on the ‘Diversity of Micro-Organisms’ for class 9, 10, 11 and 12. Find paragraphs, long and short term papers on the ‘Diversity of Micro-Organisms’ especially written for school and college students.
Diversity of Micro-Organisms
Term Paper Contents:
- Term Paper on Micro-Organisms and their Importance in Biotechnology
- Term Paper on the Role of Micro-Organisms in Decomposition
- Term Paper on the Roles of Bacteria and Fungi in Food Production
- Term Paper on the Application of Micro-Organisms in Industrial Biotechnology
- Term Paper on Micro-Organisms in the Production of Antibiotics
- Term Paper on Single-Cell Protein Production by Micro-Organisms
ADVERTISEMENTS:
Term Paper # 1. Micro-Organisms and their Importance in Biotechnology:
ADVERTISEMENTS:
All organisms are collections of chemical molecules which, when working together, show what are known as the ‘characteristics of life’. These are- respiration, reproduction, excretion, nutrition, sensitivity, growth, movement and a cellular structure.
Micro-organisms are organisms which are studied only with the aid of a microscope. Often, they are made up of one cell only (i.e. they are unicellular).
A. Viruses:
ADVERTISEMENTS:
Viruses are such simple organisms that biologists do not regard them as truly living.
They have the following main characteristics:
(i) They are less than 300 nm in size – around 50 times smaller than a bacterium (1 nm, or nanometre, is one thousand millionth of a metre). They can be seen only with an electron microscope.
(ii) They contain nucleic acid (DNA or RNA).
(iii) The nucleic acid is surrounded by a coat (two, in the case of HIV) of protein (known as the capsid).
(iv) They can reproduce only inside living (‘host’) cells.
(v) They are parasites, and cause disease (they are pathogenic).
Examples of diseases caused by viruses are influenza, measles and AIDS.
ADVERTISEMENTS:
(vi) Viruses are not affected by antibiotics.
B. Bacteria:
Bacteria are the simplest of the (truly) living organisms.
They have the following characteristics:
ADVERTISEMENTS:
(i) They have a size in the range of 0.5-5 µm (1 µm = 1/1000 mm).
(ii) They are unicellular.
(iii) They have no true nucleus (their DNA lies ‘loose’ in the cytoplasm).
(iv) They have a cell wall.
ADVERTISEMENTS:
(v) They may be (pathogenic) parasites or they may be saprotrophs – feeding on dead organic matter causing it to decay. Some may be involved in nitrogen fixation (see the section on the nitrogen cycle, below).
(vi) They are killed by antibiotics.
C. Fungi:
ADVERTISEMENTS:
Fungi are usually much larger organisms, visible to the naked eye.
They have the following characteristics:
(i) They have no chlorophyll, and thus have heterotrophic nutrition: digesting large molecules with enzymes and absorbing the soluble products. They are parasites or saprotrophs.
(ii) They have a ‘cell’ wall made of chitin.
(iii) They are usually made of a large number of tubular threads (hyphae) intertwined to form a mycelium.
ADVERTISEMENTS:
(iv) Hyphae are not divided into individual cells. The lining of cytoplasm has many nuclei and the central space in the hyphae is a vacuole full of (vacuolar) sap.
(v) If they store carbohydrate, they store glycogen.
(vi) They reproduce by producing spores.
Term Paper # 2. The Role of Micro-Organisms in Decomposition:
Many micro-organisms such as bacteria and fungi feed as saprotrophs, using external digestion. They release enzymes onto their dead organic substrate (‘food’).
These enzymes are:
ADVERTISEMENTS:
(i) Protease which digests proteins to amino acids. Amino acids are then further broken down to ammonium ions.
(ii) Amylase which digests starch to simple sugars.
(iii) Lipase which digests fats to fatty acids and glycerol.
Some of the end-products are absorbed by the micro-organisms for use in their own metabolism. For example, amino acids for building up proteins during growth; sugars for energy release during respiration – with CO2 and H2O as waste products; fats for energy storage. Gradually, the dead matter is broken down, releasing its mineral ions which are returned to the soil for recycling as they are taken up for use by plants.
Term Paper # 3. The Roles of Bacteria and Fungi in Food Production:
A. Bacteria and Yoghurt:
Milk is heated to 90°C, and then cooled to between 40°C and 45°C. The correct species of bacterium (e.g. Lactobacillus) is added and the milk is kept at this temperature for 24-36 hours. Over this time the bacteria convert milk sugar (lactose) into lactic acid by anaerobic respiration. The acid curdles the milk to produce the characteristic texture and sharp flavour of yoghurt.
B. Bacteria and Cheese:
Milk is warmed to 40°C, inoculated with bacteria (e.g. Streptococcus) and mixed with rennin, an enzyme found in the stomachs of young mammals. Lactic acid produced by the bacteria creates the correct pH for the rennin to work. The milk clots. The solid part (the curd) is separated from the liquid (the whey). The curds are pressed and moulded and left to mature, or ripen. Sometimes, further bacteria are added to provide flavour, e.g. from copper wires which are drawn through the dried curds.
C. Yeast and Alcohol:
Yeast is a fungus that is added to a sugar solution to make alcohol. For example, to make wine, yeast is added to fruit sugar from grapes; to make beer, it is added to maltose from barley. The yeast is allowed to ferment the sugar at a controlled temperature in a vessel called a fermenter. The optimum temperature for the growth of yeast is around 20°C.
The yeast converts the sugar to alcohol by anaerobic respiration, with carbon dioxide evolved as a waste product. As the concentration of alcohol rises, it eventually kills the yeast, which must then be filtered from the liquor to produce a yeast-free alcoholic drink. Drinks with a higher alcoholic content, such as spirits, are produced by distillation of the original alcoholic drink. For example, brandy is distilled wine.
D. Yeast and Bread:
ADVERTISEMENTS:
A process similar to the one described above occurs in bread-making. Flour and water are used to make a dough, then yeast and a little sugar are added. Although alcohol is produced by the anaerobic respiration of the yeast, it is the carbon dioxide which is important.
The mixture is left in a warm place for around half an hour (depending on temperature) for the dough to ‘prove’. The carbon dioxide gas causes the dough to rise, giving it a light texture. The dough is then baked at high temperature in an oven. The high temperature cooks the bread and also evaporates the alcohol produced during fermentation.
Term Paper # 4. Application of Micro-Organisms in Industrial Biotechnology:
Industrial biotechnology is the use of micro-organisms in industrial processes, for example, in the manufacture of antibiotics and single-cell protein (SCP). Large quantities of end-product (antibiotic or SCP) are required, so the micro-organisms involved are grown in very large containers called fermenters.
A maximum rate of growth of the micro-organism within the fermenter can be achieved by careful control of:
(i) The temperature
(ii) The type and concentration of substrate (i.e. the substance on which the micro-organism works)
(iii) The oxygen availability.
Thus, fermenters are unaffected by climate, soil type or, in temperate regions, time of year. Fermenters must be kept sterile to prevent the growth of unwanted species of micro-organism which might contaminate the end-product.
Term Paper # 5. Micro-Organisms in the Production of Antibiotics:
Pathogenic (disease-causing) bacteria are killed by certain chemicals (antibiotics) released by other micro-organisms, especially fungi. For example, the mould fungus Penicillium, which grows naturally on stale bread, may be cultured on a sterile medium in a laboratory. The fungus is then introduced into a fermenter for commercial production. The fermenter (up to 100,000 litres in volume) contains a suitable sterile medium on which the fungus can grow.
After an appropriate period of time, when the rate of fungal growth becomes limited by the amount of food available, the contents of the fermenter are crushed and filtered. The liquid part contains the antibiotic (in this case, penicillin), which is separated and purified. The rest of the material may be dried and used as cattle feed.
Term Paper # 6. Single-Cell Protein Production by Micro-Organisms:
Bacteria and fungi contain cytoplasm, and a major constituent of cytoplasm is protein. Therefore, large-scale production of bacteria and fungi involves the large-scale production of protein. The micro-organisms can be grown in a fermenter, harvested and used as a protein source, known as SCP If the micro-organisms involved are fungi, then, more accurately, the protein is known as mycoprotein.
Many micro-organisms will grow successfully on industrial waste materials as a substrate. Examples are- waste from oil refining, waste from sugar refining (molasses), whey from cheese manufacture, and straw.
