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MHT-CET : Biology Entrance Exam

MHT - CET : Biology - Biotechnology Page 1

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  • Biotechnology, is the term used for techniques of managing biological systems for human benefit. It includes industrial exploitation of various biological processes.
  • Fermentation by yeast for the commercial production of alcohol has been practised since a very long time.
  • Practical applications of biotechnology:
    1. Production of alcohol by fermentation.
    2. Production of drugs and chemicals.
    3. Detection of diseases and their cure by recombinant DNA technology.
    4. Production of hybrids by tissue culture.
    5. Production of economically important plants which are resistant to diseases, pests, drought, etc.
    6. Production of antibiotics, vitamins, enzymes and alcoholic beverages. .





  • Fermentation is a process in which chemical changes are brought about in an organic substrate by the action of enzymes secreted by some micro-organisms.
  • Fermenters are Mainly of Two Types:
    (1) Stirred tank fermenter - used for production of antibiotics.
    (2) Tubular tower fermenter - used for the production of alcohol.
  • A fermenter is a large vessel which is made up of either aluminium or steel.
  • It has an agitator for mixing of medium and a tank for the addition of buffers, nutrients, etc.
  • Fermentation can be done by Two Techniques:
    (1) Batch Process: In this case, the fermenter is drained and the material is separated from the broth by various means such as extraction or filtration.

    (2) Continuous Process: In this case, the fermenter is not drained. The addition of inoculum and feed and the removal of broth takes place simultaneously at regular intervals.
  • The operations before starting the fermenter are referred to as upstream processes.
  • The operation done after the fermentation is carried out are referred to as downstream processes.
  • Economic Importance of Fermentation
    1. Fermentation is used for the commercial production of alcohol, i.e., beverages like whisky, brandy, rum, etc.
    2. It is used in dairy industries for the manufacture of butter, cheese and other milk based products.
    3. It is used for the production of antibiotics, vitamins and the hormone insulin.
    4. It is used for the production of some nucleic acids and amino acids.
    5. It is also used for the production of biomass.



Manufacture of Alcohol


  • Alcohol is produced by microbial fermentation on a large scale.
  • The micro-organism which is generally used for this purpose is yeast - Saccharomyces cerevisiae.
  • The raw material generally used is molasses from sugar industry.
  • The Upstream Processes include:
    (i) Diluting the molasses with water so as to bring the concentration of sugar to 10-18%.

    (ii) Transferring them to the fermenter.

    (iii) Sterilising the fermenter and the medium.

    (iv) Adding the yeast strain which secretes the enzyme zymase.

    (v) Keeping the substrate for 2-3 days at pH 5. 0 and temperature 27C.

    (vi) Obtaining alcohol from fermented broth by distillation.
  • The Chemical Reactions Involved in this Process are:

  • The Downstream Processes Include:

    Separation, purification, distillation and redistillation to obtain different grades of alcohol.
  • Alcoholic fermentation is also carried out in a tubular tower fermenter for continuous fermentation to obtain wine or beer.
  • Uses of Alcohol are as follows:
    1. It is used in the preparation of alcoholic beverages.
    2. It is used in industries as it is a good solvent.
    3. It is used as a raw material for making chemicals and some drugs.
    4. It is a good dehydrating agent and is used in many research laboratories.
    5. It is also used as an antiseptic in medicine.





  • Antibiotics are complex organic compounds produced by certain micro-organisms which have the capacity to kill or inhibit the growth of other micro-organisms.
  • A stirred - tank fermenter is generally used for the commercial production of antibiotics.
  • The pure culture of specific micro-organism is added to the nutrient medium.
  • The temperature and pH of the fermenter is also adjusted depending upon the type of antibiotic to be produced.
  • This process is aerobic in contrast to alcoholic fermentation.
  • Common antibiotics their microbial origin and uses:


Microbial origin

Used in the treatment of</TD< tr>


Penicillium notatum, Penicillium chrysogenum

Gonorrhoea, syphilis, pharyngitis, burns and wounds, etc.


Streptomyces griseus

Tuberculosis and intestinal tract infections.


Streptomyces erythreus

Some kinds of pneumonia, scarlet fever and infections caused by gram positive bacteria.


Streptomyces venezeulae

Rocky mounted spotted fever and typhoid fever.


Streptomyces fradiae

Skin infection caused by Gram positive and Gram negative bacteria.


Streptomyces pimpriana

Plant pathogens.


Bacillus licheniformis

Tropical infections of eye and skin and burn infections.






  • Vitamins are vital organic compounds needed by the body in small amountS for the proper growth and healthy development.
  • Deficiency of vitamins causes many diseases. For example, deficiency of vitamin C causes scurvy.
  • Vitamin B2 and B12 can be produced by biotechnical methods.
  • The micro-organism used in case of production of vitamin B12 (cobalamine) is pseumonas denitrificans, streptomyces griseus, etc.
  • 2-10ppm cobalt chloride is added to the medium to increase the production of this vitamin.
  • Vigorous agitation and good aeration is also required for maximum production.
  • The micro-organism used in case by production of vitamin B2 (riboflavin) are candida flaveri, ashbya gossypii or bytylicum.
  • Cobalt chloride is not added to the medium in this case.
  • The rest of the procedure followed for the production of this vitamin is same as for vitamin B12.


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