Microorganisms

IMPORTANT TERMS

Fermentation       Process of conversion of sugar into an acid by the action of microorganisms.

Pasteurisation    Process of heating a food to a specific temperature for a specific period of time in order to kill harmful microorganisms.

Preservatives     Chemicals used to check the growth of microorganisms in food stuffs.

Communicable diseases         Diseases that can spread from an infected person to a healthy person through air, water, food or physical contact.

Antibody            Protein produced by body that fights and destroys the disease-causing microbe.

Antibiotic            A substance capable of destroying or weakening certain microorganisms.

Immunity           Immunity is the ability of the body to resist infection by an invading pathogen. The body’s immune response prevents the occurrence of diseases.

Vaccine             A preparation of dead or weakened disease-causing microbes.

Vaccination        Process by which vaccine is given to improve the immunity of the body against specific disease.

Pathogen                Microorganisms that cause diseases in human beings, plants and animals.

Carriers             Insects that transmit pathogens from an infected person to a healthy one.

Nitrification         Process of converting ammonia into nitrates through nitrifying bacteria.

 

MICROORGANISMS

Organisms that are so small that they cannot be viewed with naked eyes and can only be seen under a microscope are called Microorganisms or microbes. Microorganisms can be divided into five major groups: Bacteria, Fungi, Algae, Protozoa and Viruses.  

 

FRIENDLY MICROORGANISMS

Some microorganisms are beneficial in many ways and are used for various purposes such as commercial, medicinal and agricultural.

COMMERCIAL USES

Microorganisms are used commercially for the large scale production of alcoholic beverages, curd, cheese, bread etc.

Yeast is a fungi used in the baking industry for making breads, cakes etc. It is also used to ferment sugars in grapes to make wine.

Lactobacillus is a bacterium that helps in the formation of curd. It multiplies in milk and converts it into curd.

MEDICINAL USES

In medical industry, microorganisms are used for making antibiotics, vaccines and food supplements etc.

Streptomycin, tetracycline and erythromycin are the examples of antibiotics that are made from fungi and bacteria.

Penicillin is an antibiotic obtained from the fungus, Penicillium.

Chlorella, a type of algae is rich in proteins and other nutrients and is used as food supplements.

AGRICULTURAL USES

In agriculture, microorganisms are used to decompose dead organisms and organic matter thereby increasing the fertility of the soil.

Rhizobium bacteria, which live in the root nodules of leguminous plants such as pea and soyabean and Blue green algae help in fixing the atmospheric nitrogen and increasing soil fertility.

HARMFUL MICROORGANISMS

Microorganisms are harmful in many ways. They cause diseases in human beings, plants and animals.  

DISEASE-CAUSING MICROORGANISMS IN HUMAN BEINGS

 

Disease	Causative microorganism	Mode of Transmission
Malaria	Protozoan	Bite of female Anopheles mosquito
Dengue	Virus	Bite of female Aedes mosquito
Typhoid	Bacterium	Contaminated food
Cholera	Bacterium	Contaminated food and water
Tuberculosis	Bacterium	Air
Poliomyelitis (Polio)	Virus	Air and Water
Chicken Pox	Virus	Air/Physical contact with the infected person
Ringworm	Fungus	Direct contact with the infected person

 

DISEASE-CAUSING MICROORGANISMS IN ANIMALS

 

Disease	Causative Pathogen	Mode of Transmission
Foot and Mouth Disease	Virus	Contact with diseased animal; air
Rinderpest	Virus	Drinking contaminated water; air
Fin Rot	Bacterium/Fungus	Dirty water
Anthrax	Bacterium	Grazing

 

DISEASE-CAUSING MICROORGANISMS IN PLANTS

 

Disease	Causative Pathogen	Mode of Transmission
Citrus Canker	Bacterium	Air
Apple Scab	Fungus	Air
Septoria Leaf Blotch	Fungus	Air
Rust of Wheat	Fungus	Air; seeds

 

 

 

FOOD PRESERVATION

Food items are prone to spoilage by microorganisms. Presence of water and heat in the food is the perfect condition for microorganisms to grow. They often produce poisonous substances, which make food unfit for consumption. Food can be preserved using various methods such as canning, pasteurisation, adding preservatives, refrigeration etc. 

 

Using chemical preservatives: Food can be preserved using various chemical preservatives. Sodium benzoate is a chemical preservative found in a variety of foods.

 

Adding salt, sugar, oil or vinegar to food items create an environment that prevents the growth of

microbes.

 

Canning is a method of preserving food items by storing them in airtight cans.

 

 

INTERESTING FACTS

 

• Anton Von Leeuwenhoek, commonly known as "the Father of Microbiology” was the first to observe and describe microorganisms.
• There are more microbes on a person’s hand than there are people on the planet.
• One single teaspoon of soil contains 1 billion bacteria & 120,000 fungi & 25,000 algae.
• There are 10 times more bacteria in an average human’s digestive system than there are cells in the entire body. This is approximately 1kg of bacteria.
• The human mouth is home to more than 500 species of bacteria.
• When a person coughs, germs can travel about 3 meters if he does not put his hands or a handkerchief over his nose and mouth.
• Cyanobacteria, also known as blue-green algae, possess features similar to both of bacteria and algae.
• It is only the female species of the Aedes mosquito that bites the human beings, causing dengue; the male Aedes mosquito do not bite human beings and feed on plants and fruit nectar.