∞ generated and posted on 2016.08.29 ∞

Carbohydrate thickening agent used to produce microbiological growth media that is either solid or semi-solid.

Agar is isolated from algae and is a galactose-based polysaccharide. When suspended in water, it has the property of melting at approximately 95°C but not solidifying until reaching temperatures of about 40°C. It also does not serve as nutrient for many organisms so remains inert when in the presence of most microorganisms.

Agar is a gelatinous substance that has been used as a thickening agent in foods longer than it has been used as a thickening agent in microbiological media, though that is not coincidental as the first use of agar in microbiology stemmed from its use already in the kitchen.