What Are the Functions of a Petri Dish?

Petri dishes are cylindrical and flat for easy stacking and handling.

Since its invention in the mid-19th century by German bacteriologist Julius Richard Petri, the petri dish has been a crucial piece of equipment in microbiology labs around the world. At a basic level, a petri dish is a sterile medium for cell growth with an added nutrition supply. This simple tool is nevertheless responsible for many of the most revolutionary discoveries about bacterial and viral growth in the last century and a half.

Medium for Culture Growth

The primary function of petri dishes is to serve as an environment that promotes rapid growth of bacterial cultures. A petri dish usually consists of a cylindrical glass plate with a solution of blood agar that provides the necessary nutrients for cell growth and medium for uninhibited growth in all three dimensions. Bacteria placed in a petri dish can grow at an exponentially higher rate than in a natural air environment.

Observing Behavior of Small Organisms

In addition to promoting rapid bacterial growth, petri dishes are also the perfect tool for observing the behavior of bacterial colonies and viruses in the agar environment. Petri dishes are designed for easy viewing with a microscope. With a petri dish, living bacterial colonies can be observed in minute detail. The effectiveness of antibacterial agents can then be observed to a high degree of accuracy.

Sterile Container in Experiments

In addition to providing a nutritive environment for bacteria, petri dishes can also act as a sterile container. When properly sealed and filled with a soy agar, a petri dish can prevent bacterial contamination of its contents during transportation or storage.

Aid in Dissection

Petri dishes are often used in the dissection of very small organs. The organ is suspended in a petri dish and placed under a microscope. The petri dish provides an ideal environment for dissection because it is transparent and holds the organ in place during the dissection. With the aid of a high-powered microscope, it is possible to make incisions at precise points on a small organ.

References

• Colorado University BSI: Isolation Techniques and Use of Petri Dish Cultures
• Science Company: Bacteria Growing Experiments in Petri Plates
• Miltenyi Biotec: Dissection of Retinas