Biology - 5090

Microorganisms and Biotechnology


Microorganisms and Biotechnology
Bacteria are useful in biotechnology and genetic engineering due to their rapid reproduction rate and their ability to form complex molecules. 

They are useful due to:

Rapid reproduction rate: microorganisms are small and easy to grow in the laboratory. It is a fast process, only taking several minutes.

Ability to make complex molecules: They have a huge range of different chemical substances.

Lack of ethical concerns: No such issues arise in society over the use of their manipulation and growth

Genetic code shared with all other organisms: Even though bacterial cells are different from those of plants and animals, they share the same genetic code of DNA. A gene from a human cell can be placed in a bacterial cell to produce human protein. 

Presence of plasmids: They are easy to transfer from one cell to another due to the presence of plasmids, which are the circular piece of DNA. Plasmids are used to transfer genes from one organism’s cell to others.

Biotechnology involves the use of microorganisms to carry out processes that make substances that humans want, for example, enzymes, proteins, hormones, fermenters, extraction of metals from their ores, etc.

Main Characteristics of Groups:

Viruses, Bacteria, and fungi


All organisms that do not contain a true nucleus

DNA is not surrounded by a nuclear membrane. It is freely present in the cytoplasm.

No membrane-bounded organelles present in them.

All enzymes needed for life are freely present in the cytoplasm.

Unicellular organisms

The cell wall is made of murein/peptidoglycan, not of cellulose.


1. Non-living organisms

They can not exist outside the host body.

It does not reproduce or show any living characteristics outside of the host cell.

It does not have a cell wall or a cell membrane.

RNA is surrounded by a protein coat.

2. Living organisms

Made of a small piece of RNA (Nucleic acid)

It enters the host cell and makes the host cell machinery hostage.

It uses its life processes for reproduction, cell division, and multiplication.


Some are unicellular, like yeast. Some are multicellular, like mushrooms.

They have a well-defined nucleus. 

Their cell wall is made up of chitin, which is a polysaccharide.

The chloroplast is absent in fungi.

They feed by parasitic and saprophytic nutrition:

-parasite, like ringworm (any organism that takes food and shelter from others)

-saprophyte (any organism that lives and feeds on organic matter)

Role of Microorganisms in Decomposition

Decomposition is the process through which bacteria and fungi break down dead, organic matter into smaller particles. These microorganisms synthesize enzymes within their cells and secrete them onto the organic matter. This process is known as extracellular digestion. The digested food gets absorbed back to these bacteria and fungi and helps them grow and reproduce. This whole process not only provides microorganisms food for their own survival but also recycles the nutrients in the ecosystem.

Role of Yeast in the Production of Bread and Ethanol

The fundamental basis for the production of bread is the production of carbon dioxide during the process of yeast fermentation. In bread making, the wheat flour is mixed with water, yeast, salt, and sugar to make a dough. The sugar causes the fermentation process to start quickly. The dough is then left in a warm, humid environment to allow fermentation. The yeast feeds on the sugar, using it as a source of carbon and energy, and breaks it down anaerobically into alcohol (ethanol) and carbon dioxide. The bubbles of carbon dioxide lead to the rising of the dough. The dough is then baked which kills the yeast and evaporates the alcohol. 

Role of Bacteria in Yogurt and Cheese Production

Yogurt and cheese are produced as a result of fermented milk. There are two species of bacteria involved, Lactobacillus and Streptococcus. The lactic acid bacteria, Lactobacillus, breaks down the lactose sugar in the milk to lactic acid, which results in a different texture and flavor.

Yogurt Production:

The milk, containing lactose, is first boiled at 90 degrees Celsius for twenty minutes to kill any unwanted bacteria and to denature the milk proteins. It is then cooled to a temperature of about 40 degrees Celsius. Then, the starter culture of the bacteria is inoculated into the milk. The bacteria will feed on the lactose, and convert it to lactic acid through the process of anaerobic fermentation. The acid will coagulate the proteins present in the milk, and thicken the yogurt. The thickened yogurt is then cooled. There is an option to add any fruit to enhance the flavor. The yogurt is packed and distributed at 2-4 degrees Celsius so the bacteria remain alive as well as inactive.

Cheese Production:

Cheese is a food product that is used worldwide. It is purely a product of microbial fermentation of milk. The milk is to be pasteurized, by heating to 72 degrees Celsius, to kill any unwanted bacteria. It is then cooled. A starter culture of bacteria is added to the milk at around 32 degrees Celsius. The bacteria convert lactose into lactic acid. The acid will coagulate the milk, separating the curd (solid part) from the whey (liquid part). Then, rennet is added which contains renin which is a protein-coagulating enzyme. After the separation of curd and whey, some flavors are added. The curd is poured into molds, then pressed to remove any remaining whey from it. Eventually, the curd hardens to form a cheese block. 

Use of Fermenters for Large-Scale Production

of Single-Cell protein (SCP)

The food processed from microorganisms, like bacteria, algae, yeasts are called single-cell protein. These organisms are single-celled and have high protein content. The microorganisms take in the nutrients in a large container, called fermenter. Some examples are as following:

Pruteen from bacteria
Chlorella from Chlorella
Mycoprotein/Quorn from fungi

Role of the Fungus Penicillium in the Production of Penicillin

Antibiotics are substances that kill the bacteria but do not harm the human cells. They are used to cure bacterial infections. Penicillin is an antibiotic and it is grown in a fermenter using the fungus Penicillium.

The water jacket of the fermenter maintains a constant temperature to prevent the denaturation of the enzymes. As the fungus respires, it releases heat so the temperature in the fermenter increases which would kill the fungus in the absence of a water jacket. The stirring paddles, as suggested by the name, stir and maintain a suspension, giving a uniform mixture. The nutrient inlet supplies glucose, ammonia and amino acids for the growth and respiration processes. The probe/sensor/data logger monitors the temperature and pH.

The air supply is present to supply oxygen for the process of aerobic respiration. The outlet allows the collection of the liquid containing penicillin after fermentation. After collection, penicillin is separated and purified from toxins. Then, it is dried up and made into pills.

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