Introduction of Plastic Petri Dish
A plastic Petri dish is a shallow, cylindrical, transparent container with a loosely fitting lid, widely used in biological laboratories for culturing microorganisms and cells. It is the modern, disposable counterpart to the original glass dish invented by Julius Richard Petri in 1887, and its adoption has greatly improved laboratory efficiency and safety.
Material and Features
Most plastic Petri dishes are manufactured from high-quality polystyrene (PS), a material chosen for its excellent optical clarity, which allows researchers to observe colony growth and cellular details clearly under a microscope. For applications requiring greater chemical resistance or reusability, some dishes are made of polypropylene (PP). Standard dishes are typically 90 mm in diameter, though other sizes like 35 mm, 60 mm, and 150 mm are available for various experimental needs. A key design feature is the lid: vented dishes have small ridges that permit essential gas exchange (CO₂ and O₂) for aerobic cultures, while non-vented dishes provide a tighter seal to reduce moisture evaporation during long-term incubation.
Advantages Over Glass
Plastic offers several practical benefits. Pre-sterilized disposable dishes eliminate the need for time-consuming washing and autoclaving, significantly reducing contamination risks and labor costs. Additionally, plastic is shatterproof, making it safer to handle and transport.
Primary Applications
Plastic Petri dishes are indispensable in microbiology for preparing agar plates to isolate, culture, and count bacteria and fungi from clinical, food, or environmental samples. They are also widely used in mammalian and plant cell culture, as well as in antimicrobial susceptibility testing, such as the Kirby-Bauer disk diffusion method.