Incubator Definition

In microbiology, an incubator is an enclosed, insulated device that offers the ideal levels of humidity, temperature, and other environmental variables needed for the development of organisms.

An incubator is a crucial piece of scientific equipment used for growing microorganisms in controlled environments.

It is possible to grow both single-celled and multicellular creatures in an incubator.

Components/Parts of the Incubator

A microbial incubator is made up of various units, some of which are:

Cabinet

• The cabinet, which has a volume varying from 20 to 800 liters, is the incubator’s primary body. It is a double-walled container.
• Aluminum is used for the inside walls, while stainless steel sheets are used for the exterior.
• Glass wool is used in the space between the two walls as an insulation material.
• The insulation guarantees the device’s smooth operation by preventing heat loss and lowering power consumption.
• Inward projections are built into the incubator’s interior wall to support the shelves that are housed inside.

Door

• Each incubator has a door that may be closed to seal the insulated cabinet.
• Additionally, the door has its own insulation. Sometimes, a window is included, allowing for a view of the incubator’s inside during incubation without disrupting the environment.
• The door has a handle on the exterior to facilitate opening and closing it.

Control Panel

• An incubator’s outside wall has a control panel with indicators and switches needed to adjust the incubator’s settings.
• The device’s thermostat is likewise controlled by a switch on the control panel.

Thermostat

• The incubator’s temperature may be adjusted using a thermostat.
• When the incubator reaches the desired temperature, the thermostat will automatically holds it until the temperature is altered or an activity causes it to change.

Perforated shelves

• Perforated shelves are attached to the interior wall to hold plates and tubes with the culture media.
• The shelves’ holes enable hot air to circulate throughout the incubator’s interior.
• Some incubators have detachable shelves, allowing for thorough cleaning of the shelves.

Asbestos door gasket

• A nearly airtight seal is provided between the door and the cabinet by the asbestos door gasket.
• This seal keeps outside air from entering the cabinet, therefore isolating the heated climate inside the cabinet and preventing interruptions from the outside world.

L-shaped thermometer

• On the upper portion of the incubator’s outside wall is a thermometer.
• The thermometer’s graduated end is left outside the incubator so that the temperature may be read easily.
• The mercury bulb’s next end is somewhat extending into the incubator’s chamber.

HEPA filters

• Certain sophisticated incubators also include HEPA filters to reduce any potential contamination brought on by airflow.
• A closed-loop system is created by an air-pump with filters, which reduces contamination from the air flowing within the incubator.

Humidity and gas control

• A reservoir with water is provided with the CO2 incubators underneath the chamber.
• To keep the relative humidity within the chamber constant, the water is used.
• Sometimes, if needed, the incubator can be adjusted as gas chambers that allow for the proper CO2 (or other gases) concentration inside the incubator.

Principle/ Working of Incubator

• The foundation of every incubator is the idea that when organisms are given the ideal conditions for temperature, humidity, oxygen levels, and carbon dioxide levels, they thrive and divide to produce offspring organisms.
• The thermostat in an incubator maintains a set temperature that may be measured with a thermometer from the outside.
• The heating and no-heating cycles are used to keep the temperature steady.
• The incubator is heated by the thermostat during the heating cycle, and the incubator is cooled by radiating heat into the environment during the no-heating phase when the thermostat is turned off.
• Insulation from the exterior produces an isolated environment within the cabinet that promotes efficient microbial growth.
• Other techniques are used to control other variables like humidity and airflow in order to produce an atmosphere that resembles the natural habitat of the creatures.
• They are also given modifications for regulating the CO2 (or other gases) concentration to balance the pH and humidity needed for the organisms to develop.
• There is also a shaking incubator variation of the incubator that enables the constant shaking of the culture needed for cell aeration and solubility experiments.

Procedure for running an incubator

• After the cultures of the organisms are established, the culture plates must be kept in an incubator for the needed amount of time and at the proper temperature. The typical temperature to be maintained in the majority of clinical laboratories for microorganisms is 35–37 °C.
• The procedures that must be followed when operating an incubator are as follows:
• It is important to check the incubator to make sure there are no leftovers from prior cycles before utilising it. However, there are some situations when numerous species can be housed in the same incubator if they all require the same set of environmental conditions.
• The incubator is then turned on while the door is kept tightly closed. The temperature of the incubator must be raised to that required for an organism’s development.
• Use the thermometer to determine whether the temperature has reached
• In the interim, the incubator’s settings should be adjusted if the organism needs a specific CO2 concentration or level of humidity.
• The petri dish cultures are put on the perforated shelves upside down, with the medium uppermost, once all the criteria have been satisfied. If the plates were incubated regularly, condensation would build up on the medium’s surface and impede the growth of isolated colonies.
• Petri dish cultures are placed in plastic bags or food storage containers and sealed with adhesive tape if it is required to incubate them for several days.
• The plates are now held in place for the necessary amount of time before being removed, and the door has been secured.

Types of incubators

The following categories of incubators are used to categorise them based on whether they include a certain parameter or what they are used for:

Benchtop incubators

• The majority of laboratories utilise this kind of incubator the most frequently.
• These are the fundamental varieties, equipped with insulation and temperature control.

CO2 incubators

• Specialized incubators that can automatically manage CO2 and humidity are known as CO2 incubators.
• This kind of incubator is used to cultivate various bacteria that need a CO2 concentration of between 5 and 10%.
• Water is maintained below the incubator’s cabinet to regulate humidity.

Cooled incubators

• Incubators are equipped with customised refrigeration systems with heating and cooling controls to allow for incubation at temperatures lower than the ambient.
• The cooling incubator is the name given to this kind of incubator.
• The heating and cooling controls in the cooling incubator should be properly balanced.

Shaker incubator

• Another device used to grow microorganisms is a thermostatically controlled shaker incubator.
• Its benefit is that it quickly and uniformly transfers heat to the culture tank, and the agitation it causes increases aeration and speeds up development.
• However, this incubator is only suitable for use with broth or liquid culture material.

Portable incubator

Smaller portable incubators are used for fieldwork such as environmental microbiology and water testing.

Uses of Incubator

• Numerous fields, including cell culture, pharmacological research, haematological analysis, and biochemical analysis, use incubators.
• Some of the uses of incubators are given below:
• Cell or microbial cultures are grown in incubators.
• Incubators can also be used to preserve an organism’s culture for later use.
• Some incubators are used to speed up the growth of organisms whose natural environments permit a slower rate of growth.
• Certain incubators are utilised for the development of microbial colonies and subsequent assessment of the biochemical oxygen requirement.
• In zoology, they are also employed for the breeding of insects and egg hatching.
• Prior to being processed in the labs, samples can be stored in incubators under regulated conditions.

Precautions

• When operating an incubator, the following safety precautions must be taken:
• The temperature of the cabinet should not be changed frequently by opening the door, since germs are sensitive to temperature changes.
• Before the culture plates are positioned on the shelves of the cabinet, the organism’s development requirements must be satisfied.
• To avoid condensation on the media, the plates should be positioned upside down with the lid at the bottom.
• To stop the organisms from congregating on the shelves or corners of the incubators, the interiors should be cleaned often.
• To keep the culture material from drying out while the incubator is being used for a long time, the shelves should be submerged in sterile water.

References

• Collins CH, Patricia M, and Lyne JM (1995). Collins and Lynes Microbiological Methods 7th edition. Grange, Butter Worth, Oxford.
• Cappucino JG and Sherman N (1996). Microbiology, A Laboratory Manual 4th edition. Benjamin Cumings Inc. California.
• https://www.atmosafe.net/en/glossary/incubator.html
• https://microbenotes.com/instruments-used-in-microbiology-lab/
• https://www.labmanager.com/product-focus/incubators-20299

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