Incubator: Definition, Principle, Components, Types, Operating Procedure, Use.

Incubator definition  An incubator is an insulated and enclosed device used in biological laboratories. It creates an optimum environment which is required...

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This article writter by MN Editors on December 01, 2020

Microbiology Notes is an educational niche blog related to microbiology (bacteriology, virology, parasitology, mycology, immunology, molecular biology, biochemistry, etc.) and different branches of biology.

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Incubator definition 

An incubator is an insulated and enclosed device used in biological laboratories. It creates an optimum environment which is required for the growth of microorganisms by providing optimum temperature, humidity, and other environmental conditions such as the CO2 and oxygen content inside’s atmosphere.

In laboratories, it is used to grow and maintain microbiological cultures or cell cultures. Both bacterial and eukaryotic cell organisms are cultivated by using an incubator.

Working Principle of Incubator 

All incubators work based on a simple principle that microorganisms require an optimum environment for their growth and development. An incubator provides an optimum level of temperature, humidity, oxygen, and carbon dioxide so that the microorganism can multiply and increase their numbers.

Incubator contain a thermostat which maintains the inside temperature of the incubator. We can monitor this temperature from the outside via the thermometer. By utilizing the heating and no-heating cycles we maintain the inside temperature of the incubator.

In heating cycle, the thermostat increases the temperature of incubator whereas in the non-heating cycle the incubator is cooled by radiating heat to the surrounding. The cabinet contains an insulation system that separates it from the outside and allows the microbes to grow effectively.

Similarly, the incubator also maintains the other parameters such as humidity, airflow, co2 concentration, pH, through different mechanisms which are required for the growth of the organisms.

Some incubators also contain a shaker or aeration device which continuously shake the culture for cell aeration and solubility studies.

Components of an Incubator

An incubator is made up of different parts or components which help to maintain the optimum condition required for the bacteria growth. The parts of an incubator are;

(i) Cabinet

  • The cabinet is made of a double-walled cuboidal enclosure. It has a capacity of 20 to 800L.
  • It consists of an inner wall which is made of aluminum and an outer wall which is made of stainless steel sheets.
  • To provide insulation to the incubator the inner gap between the inner wall and outer wall is filled with glass wool. It prevents heat loss from the incubator.

(ii) Door

  • The incubator contains an insulated door that encloses the insulated cabinet. 
  • There also presents a glass door that enables the visualization of the interior of the incubator.

(iii) Control Panel

  • It is located at the outer of the incubator. It consists of many switches and indicators which monitor the different parameters of the incubator.
  • It also controlled the thermostat device.

(iv) Thermostat

  • It is used to achieve the desired temperature within the incubator.
  • It constantly maintains the specified temperature within the incubator by the heating and no-heating cycles.

(v) Perforated shelves

  • It is located on the inner wall of the incubator. The plates of culture media are placed over it.
  • These shelves are removed, which means we can clean them properly.
  • The shelves contain perforations which help in the movement of hot air throughout the inside of the incubator.

(vi) Asbestos door gasket

  • It provides an airtight seal between the door and the cabinet.
  • It separates the hot environment of the cabinet from the external environment and prevents the outside air from entering the cabinet.
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(vii) L-shaped thermometer

  • It is located on the top part of the outer wall of the incubator.
  • One end of this thermometer contains gradations which indicate the inside temperature of the incubator.
  • Another end of this thermometer contains a mercury bulb which is located within the incubator.

(viii) HEPA filters

  • Some incubators also contain HEPA filters, it helps to reduce the contamination which is created by the airflow.
  • It is connected with an air-pump which circulates the air within the incubator so it creates a closed-loop system to reduce the chances of contamination.

(ix) Humidity and gas control

  • A water source or reservoir is located underneath the chamber. This water is vaporized to control the relative humidity inside the incubator.
  • It also contains a gas chamber that maintains the CO2 concentration within the incubator.

Types of Incubator in laboratory

There are different  types of incubators in microbiology. These are classified based on the types of parameters or the purpose of the incubator.

  1. Benchtop incubators: Most of the laboratories contain Benchtop incubators. It has a basic function of temperature control and insulation.
  2. Shaker incubator: It contains a shaker which continuously shakes the culture media for proper aeration. It transfers the heat uniformly within the incubator.
  3. CO2 incubators: This type of incubator automatically controls the CO2 and humidity within the chamber.
  4. Cooled incubators: It is also known as a cooling incubator. They contain a refrigeration system with heating and cooling functionality. It is used to incubate the culture media at temperatures below the ambient. The heating and cooling controls of this incubator should be appropriately balanced.

Operating Procedure of an incubator

After preparation of culture, it needs to be stored in an incubator at the desired temperature, co2 concentration for a period of time. 

  1. Before run an incubator make sure there are no remaining items present from the previous cycles. 
  2. If different organisms require the same parameters then keep them in the same incubator.
  3. Then close the door and switch on the incubator. Make sure the door is properly closed.
  4. Now set the desired temperature in the controller and keep monitoring it through the thermometer.
  5. If any organism requires a specific concentration of CO2 or a specific humidity then we also can set them in the controller.
  6. After setting the parameters, place the culture plates on the perforated shelves upside down.
  7. It is necessary to seal the plates with adhesive tapes or are placed in plastic bags to prevent contamination.

Application of Incubator

In laboratories incubator is used for different purpose such as;

  1. Used to maintain the growth of different microbial cultures or cell cultures, which we can use in later.
  2. Sometimes they are used to enhance the growth rate of organisms.
  3. Some advanced incubators are used for the reproduction of microbial colonies and subsequent determination of biochemical oxygen demand.
  4. In zoology, they are also used for the breeding of insects and hatching of eggs.
  5. It also used to store different medical samples.


  1. Before run an incubator make sure there is enough water present underneath the shelves, otherwise the culture media will be drying out.
  2. Clean the incubator regularly, otherwise organisms will settle down on the shelves or the corners of the incubator.
  3. To avoid the condensation of water onto the media placed the plates upside down with the lid at the bottom.
  4. Before placing the culture plates inside the incubator make sure the desire parameters are achieved.
  5. Avoid repeated opening of the door when the incubator is running.

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Microbiology Notes is an educational niche blog related to microbiology (bacteriology, virology, parasitology, mycology, immunology, molecular biology, biochemistry, etc.) and different branches of biology.

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