Question

What is the usual concentration of agar in most culture media?

a) 0.5 - 1%
b) 1 - 2%
c) 2 - 3%
d) 3 - 4%

Answer 1

The correct option is b). The common concentration of agar in culture media is between 1 - 2%, utilized for its inert properties to facilitate bacterial growth and colony observation.

Step-by-step explanation:

The usual concentration of agar in most culture media is between 1 - 2%. Agar is a polysaccharide that is derived from red seaweed, which acts as a solidifying agent for creating a solid growth surface. It is preferred for its inert and non-nutritive properties, allowing for the observation of bacterial colonies as they reproduce. When preparing solid media, accurate measurement of agar concentration is key to ensure the desired consistency and efficacy for microbial growth and analysis.

In laboratory settings, solidifying agents like agar are crucial for tissue culture studies, bacterial culture density assessments, and other microbiological applications. For example, Tryptic Soy Agar plates often use agar to create the solid medium needed for bacterial growth, allowing for the identification and enumeration of specific bacterial colonies.