Petri Dish - Functions, Types and Uses

A Petri dish is a fundamental tool in microbiology and various scientific fields, designed for culturing and observing microorganisms and cell cultures. Its simple yet effective design allows researchers to create controlled environments for growth and experimentation. In this blog, we'll explore what a Petri dish is used for, the different types available, and how to use it effectively. We'll also look into its various petri dish functions and applications in research and petri dish used in laboratory settings.

What is a Petri Dish?

A Petri dish is a shallow, transparent dish with a lid, primarily used in biological experiments for culturing cells. In microbiology, it serves as a container for growing microbes using various growth media. Named after its inventor, German bacteriologist Julius Richard Petri, it is also known as a Petri plate or culture plate.

Why to use a Petri Dish?

Uses of a Petri Dish:

• Culturing Cells: Provides a controlled environment for growing cells and microorganisms.
• Observing Growth: Transparent design allows for easy observation of microbial growth without disturbing the culture.
• Educational Projects: Useful in science projects, such as observing seed germination.
• Measuring Culture Density: Some dishes feature grids on the bottom for quantifying microbial growth.
• Sample Storage: Suitable for storing samples in liquid or granular form, including small objects like insects and seeds.
• Drying and Evaporation: Facilitates the drying and evaporation of samples.

Types of Petri Dish:

Based on Shape:

• Cylindrical: The most common type, with diameters ranging from 30 to 200 millimeters.
• Square and Rectangular: Available for specific applications where traditional shapes are less suitable.

Based on Usability:

• Reusable: Made from durable materials that can withstand repeated sterilization, such as borosilicate glass.
• Disposable: Typically made from plastics, used for single-use to prevent contamination.

Based on Material:

Glass: Often borosilicate glass, heat-resistant and suitable for autoclaving at 120-160°C.

Plastic: Includes various types of Polylab Petri Dish.

·       Polystyrene: Disposable, cost-effective, widely used for routine testing.

·       Polypropylene: Lightweight, heat, and chemical resistant, more durable than glass.

               

·       Cellulose Acetate: Offers greater gas permeability for applications requiring higher oxygen and carbon dioxide levels.

·       Nitrile: Suitable for low-temperature applications, with a range of -30°F to 275°F.

 

Based on Compartments:

• Single Compartment: Standard Petri dish for general.
• Multiple Compartments: Ranges from 2 to 4 compartments for preparing multiple culture media in one plate.
  
  

Parts of a Petri Dish:

The parts of a Petri dish include:

• Transparent Container: The main body of the dish, which is clear to allow easy observation of the cultures.
• Lid/Cover: A removable cover that protects the contents from contamination and evaporation.
• Bottom Dish: The larger part that holds the growth medium and provides a stable base. It is typically flat with a slightly ridged rim to prevent spillage of the medium.
• Sealing: Often sealed with parafilm to maintain a sterile environment.
• Labelling Area: The bottom dish is usually labelled with the date, sample name, type of medium, and any other relevant details for accurate identification and tracking.
  
  

Uses of Petri Dish:

Petri dishes used in various applications, including:

• Growing Skin Grafts and Organoids: Ideal for developing and studying tissue cultures.
• Researching Seedlings: Petri dish useful for monitoring the early stages of plant development.
• Observing Insect Activity: Provides a controlled setting to study insects.
• Evaporating Solvents and Precipitates: Employed in chemical labs for drying and concentrating substances.

How to use a Petri Dish?

A common application is creating agar plates. Here’s a simple procedure for petri dish use:

Prepare Agar Mixture: Combine agar with distilled water, and if needed, add nutrient broth or other growth media.

Sterilize:  Autoclave the media for 20 minutes. Cool until manageable (approx. 42°C). Pour about 12 ml into sterile Petri dishes and let them solidify.

Cool: Shake the culture, flame an inoculation loop, and cool it. Inoculate the Petri dish by streaking lines with the loop. Flame the loop between streaking.

Pour and Solidify: Pour the cooled agar into sterile Petri plates, filling them to about ¼ or ½ inch depth. Swirl to distribute evenly and let solidify.

Seal and Store: Cover the plates with lids and wrap with parafilm to prevent drying and contamination. Store in the refrigerator until needed.

Functions of a Petri Dish:

Following are the petri dish functions.

Culturing Cells: Provides a sterile environment for growing and observing microorganisms, fungi, or cells.

Storing Samples: Used to store and examine samples such as seeds, insects, or small objects in a controlled setting.

Agar Plate Creation: Essential for preparing agar plates petri dish used in microbiological experiments and testing.

Growth Observation: Facilitates the visual observation and measurement of microbial growth patterns and culture density.

Educational Demonstrations: Commonly used in educational settings to illustrate biological processes, including germination and microbial development.

In conclusion, Petri dishes are fundamental tools in both scientific research and practical applications. Their ability to provide a controlled, sterile environment makes them invaluable for growing and observing microorganisms, developing tissue cultures, and conducting various experiments. Whether used for educational purposes, microbial research, or chemical analysis, Petri dishes offer a clear, versatile platform that aids in precise observations and experiments. Their diverse functions and adaptability continue to make them an essential component in laboratories and educational petri dish use settings around the world.