Agar plate

Agar plate is a petri dish that contains agar as a solid growth medium plus nutrients, used to culture microorganisms. Sometimes selective compounds are added to influence growth, such as antibiotics.

History[edit | edit source]

The agar plate was developed by the German physician Richard Julius Petri in 1887, while working as an assistant to Robert Koch, the founder of modern bacteriology.

Preparation and use[edit | edit source]

To prepare an agar plate, a scientist pours a liquid containing agar, nutrients, and possibly other ingredients into a petri dish, then allows the liquid to cool and solidify. Once the agar solidifies, it forms a jelly-like substance in the dish.

Microorganisms can be cultured in the agar plate by streaking a sample across the surface of the agar with an inoculating loop. The microorganisms grow into separate colonies, each a clone of the original microbe in the sample.

Types of agar plates[edit | edit source]

There are many types of agar plates, each designed for specific purposes. Some common types include:

Nutrient agar plates: These are used to culture a wide variety of microorganisms. They contain beef extract and peptone.
Sabouraud agar plates: These are used to culture fungi and contain antibiotics to inhibit bacterial growth.
MacConkey agar plates: These are used to differentiate between lactose fermenting and non-lactose fermenting Gram-negative bacteria.
Blood agar plates: These are used to culture bacteria that require blood to grow.

References[edit | edit source]

Agar plate Resources
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