A cell culture dish, also known as a culture dish or agar plate, is a shallow, circular glass or plastic dish that scientists use to culture microorganisms and small plant tissues on a solid growth medium. Cell culture dishes feature a cover that seals the dish to protect the contents from contamination while allowing observation from above. They provide an ideal sterile environment for microbes to grow where they can be easily viewed and analyzed under a microscope.

History of the Petri Dish

The modern cell culture dish was invented in the late 19th century by German microbiologist Julius Richard Petri to enable the cultivation and study of bacteria and fungi. Prior to the cell culture dish, microbiologists used other methods like hanging drop slides that were more difficult to work with. Petri noticed bacteria grew more easily when spread over the surface of a solid gel instead of in liquid culture. His invention of the shallow, circular dish enabled easy culturing and observation of microbes in a controlled manner. Since then, cell culture dishes have become an indispensable laboratory tool essential for microbiology research and teaching.

Components and Construction

A typical cell culture Petri Dish consists of a transparent flat lid and a shallow circular body, usually made of glass or sterile plastic. The bottom of the dish features a cover slip to allow for microscopic examination from below. To use a cell culture dish, a sterile solid growth medium like nutrient agar or gelatin is poured into the sterile dish and allowed to solidify. This provides microorganisms with nutrients while keeping them immobilized on a flat surface for easy detection, counting and isolation. The clear lid seals the dish to maintain sterility during incubation by preventing contamination from airborne microbes.

Uses of Cell culture dishes in Microbiology

There are several important uses of cell culture dishes in microbiology laboratories:

Bacterial and Fungal Culturing - Cell culture dishes with various nutrient agars are commonly used to culture, isolate and grow bacterial colonies from clinical, environmental or food samples. Different agars select for different microbes.

Antibiotic Sensitivity Testing - Dishes with antibiotic-containing agar help determine which antibiotics a certain bacterial strain may be sensitive or resistant to through zone of inhibition tests.

Genetic Engineering - Dishes with particular nutrient agars help screen genetically modified bacteria by selecting for or against desired genes and phenotypes during plasmid transformation experiments.

Enumeration and Isolation - Spread plating a diluted sample onto multiple dishes enables counting of microbial colonies after incubation, isolating pure cultures through sub-culturing.

Storage - Agar slants in tubes or plates provide a sterile substrate to store microbial cultures long-term in refrigerators or freezers.

Contamination Testing - Dishes help detect presence of spoilage microbes on food, water or industrial products through presence/absence testing.

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