What common medium is used to culture microorganisms?

Agar is a gelatinous substance derived from seaweed that serves as an essential medium for culturing microorganisms in laboratories. It provides a stable and nutritious environment that supports the growth of bacteria, fungi, and other microorganisms. As a solid medium, agar allows for the formation of distinct colonies, which can be observed and analyzed. It is widely used due to its ability to solidify at room temperature and remain stable while providing a surface for microbial growth.

In various applications, agar can be enriched with specific nutrients, antibiotics, or dyes to selectively promote the growth of certain organisms or observe particular characteristics. This versatility makes agar an ideal choice for microbiological studies and experimentation.

While plasma and water might seem like potential growth media, they do not offer the structured support and nutrient-rich conditions provided by agar. Stains, on the other hand, are used to visualize microorganisms rather than cultivate them, further distinguishing agar as the correct choice in this context.