Fermentation : Defination, Principle and Batch Fermentation Method

 The process of fermentation involves biochemical activity of organisms during their growth, development, reproduction, senescence, and death. Fermentation technology employs organisms to produce food, pharmaceuticals, and alcoholic beverages in industries on a large scale.

Principle of Fermentation

The principle involved in industrial fermentation technology is that organisms are grown under optimum conditions and are provided with raw materials and other necessary requirements like carbon, nitrogen, salts, trace elements, and vitamins. The end products formed due to their metabolism during their life span are released into the media. These end products are extracted by human beings as they are commercially valuable.

Some major end products of fermentation produced on a large scale industrial basis are wine, beer, cider, vinegar, ethanol, cheese, hormones, antibiotics, complete proteins, enzymes, and other beneficial products.

Batch Fermentation

In batch fermentation process, the microorganisms are inoculated in a fixed volume of batch culture medium. The organisms during their growth consume the nutrients, and the growth products (i.e., biomass and metabolites) start accumulating. Since the nutrient environment within the Fermenter is continuously changed, the rate of cell metabolism also changes, and ultimately, cell multiplication stops due to limitation of nutrients and accumulation of toxic excreted waste products.

Growth Characteristics in a Batch Culture of a Microorganism. 1) Lag Phase, 2) Transient Acceleration, 3) Exponential Phase, 4) Deceleration Phase, 5) Stationary Phase, 6) Death Phase

There is the complex nature of batch growth of microorganisms. In the initial lag phase, no apparent growth is observed; however, biochemical analyses show metabolic turnover signifying that the cells are acclimatising to the environmental conditions and will start growing. Then comes the transient acceleration phase when the inoculum begins to grow. This phase is quickly followed by the exponential phase where the organisms are growing at fastest rate as the nutrients are in excess, environmental conditions are optimum and growth inhibitors are absent.

In the batch fermentation process, the exponential growth occurs for a limited period. With the change in nutrient conditions, the growth rate decreases and begins deceleration phase followed by the stationary phase at which the growth sto completely because of nutrient exhaustion. The death phase when the grow rate has come to an end is the final phase of the cycle. Mostly t biotechnological batch processes are stopped before this stage because decreasing metabolism and cell lysis.

Advantages of Batch Fermentation

  1. It Requires less space.
  2. It Can be easily handled, and
  3. There is Less chances of contamination.

Disadvantages of Batch Fermentation

  1. It is time consuming method.
  2. It requires more time for cleaning, sterilisation, and cooling.
  3. Product yield is low.

Applications of rDNA Technology and Genetic Engineering in Medicine

 Genetic engineering has an important role to play in the production of medicines. Microorganisms and plant-based substances are used for producing various drugs, vaccines, enzymes, and hormones at low costs. Genetic engineering involves the study of inheritance pattern of diseases in man and collection of human genes that provide a complete map for inheritance of healthy individuals.


  Recombinant DNA technology is used for producing vaccines against diseases by isolating antigen or protein present on the surface of viral particles. Vaccines contain a form of an infectious organism that does not cause disease but allow the body immune system to form antibodies against the infective organism.

   When an individual receives vaccination against any viral disease, the antigens produce antibodies to act against and inactivate the viral profeins. The scientists with the help of recombinant DNA technology have transferred the genes for some viral sheath proteins to vecinia virus which was used against small pox. Vaccines produced by gene cloning are non-contaminated and safe as they contain only coat proteins against which antibodies are produced. Vaccines against viral hepatitis influenza, herpes simplex virus, virus-induced foot and mouth disease in animals are being produced by gene cloning.


  Insulin was commercially produced in 1982 through biogenetic or recombinant DNA technology. Its medicinal use was approved by Food and Drug Administration (FDA) of the USA in the same year. The human insulin gene has been cloned in large quantities in E. coli bacterium that can be used for synthesising insulin. Humilin is the commercially available genetically engineered insulin.


Lymphokines are proteins regulating the immune system in the human body. u. Interferon is an example of lymphokines that are used to fight viral diseases (such as hepatitis, herpes, and common cold) and cancer. Such drugs can be manufactured in large quantities in bacterial cells. Lymphokines are also helpful in AIDS. Interleukin-II is a commercially available genetically engineered substance that stimulates the multiplication of lymphocytes.


  Somatostatin is used in some of the growth related abnormalities. This drug appears to be species specific and the polypeptide obtained from other mammals has no effect on humans, hence it is extracted from the hypothalamus of cadavers. Genetic engineering has helped in the chemical synthesis of gene which is joined to the PBR 322 plasmid DNA and cloned into a bacterium. This transformed bacterium is converted into a somatostatin synthesising factory.

Production of Blood Clotting Factors

  Blockage of coronary arteries by cholesterol or blood clots causes heart attack. Plasminogen is a substance found in blood clots. Genetically engineered tissue Plasminogen Activator (tPA) enzyme is used to dissolve these clots in individuals who have suffered heart attacks.


  Antibodies cloned from a single source and targeted for a specific antigen (monoclonal antibodies) have proved useful in the treatment of cancer. Monoclonal antibodies have been targeted with radioactive elements of cytotoxins (e.g., Ricin from castor seed) to make them more deadly. Such antibodies seek cancer cells and kill them with their radioactivity or toxin.