agarplaten

An agar plate is a shallow, circular dish containing a solid growth medium made with agar, a gelatinous polysaccharide derived from red algae. The medium provides nutrients and a stable surface on which microorganisms can grow into visible colonies. Agar remains solid over a wide range of incubation temperatures, allowing easy observation and isolation of distinct colonies.

Most plates use a nutrient-based medium, such as nutrient agar or trypticase soy agar, but formulations can be adjusted to support the growth of specific organisms or to differentiate among them. Selective and differential media, for example MacConkey agar for Gram-negative bacteria or Sabouraud dextrose agar for fungi, help researchers identify or isolate particular groups based on growth patterns and color changes.

Agar plates have a notable historical role in microbiology. Agar was adopted as a solidifying agent in the late 19th century, enabling the development of reproducible culture techniques that underpinned many foundational discoveries in microbiology.

In typical laboratory practice, plates are prepared with sterile media, poured into Petri dishes, and allowed to solidify before use. After inoculation, plates are incubated under conditions appropriate for the organism of interest, with growth observed as colonies. Plates are commonly stored inverted to prevent condensation from disturbing the surface.

Safety and handling considerations emphasize aseptic technique and proper biosafety practices. Agar plates are intended for research and diagnostic use and are not designed for consumption.