OperationConnect Group

The Petri dish is one of the most simple yet fundamentally important pieces of equipment in the life sciences, consisting of a shallow cylindrical glass or plastic dish with a loose-fitting lid that is essential for culturing microorganisms and cells. Invented in 1887 by German bacteriologist Julius Richard Petri, who was an assistant to the pioneering scientist Robert Koch, the dish replaced earlier, less effective methods for growing pure cultures of bacteria. Its design, particularly the overlapping lid, provides a sterile, contained environment, which is paramount for preventing airborne contamination of the nutrient medium within.

The primary use of the Petri dish is for growing microbiological cultures. The dish is typically filled with a solidified nutrient medium, most commonly agar, which provides the necessary food and water for the growth of bacteria, fungi, or other microorganisms. Samples are either streaked across the surface of the agar or mixed into the medium before it solidifies. The culture is then placed in an incubator at an optimal temperature, allowing individual cells to divide repeatedly until they form visible, localized masses called colonies. The isolation of these pure colonies is a foundational technique for identifying specific types of microbes, conducting antibiotic sensitivity testing, and studying bacterial genetics.