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a dried hydrophilic, colloidal product obtained from certain species of red algae. Because it is unaffected by bacterial enzymes, it is widely used as the basic ingredient in solid culture media in bacteriology. Agar-agar is also used as a suspending medium, as an emulsifying agent, and as a bulk laxative. Also called agar.
agar, agar-agar (ag′ăr) (ag′ăr-ag′ăr) [Malay, gelatin]
1. A dried mucilaginous product obtained from certain species of algae, esp. of the genus Gelidium. Agar is unaffected by bacterial enzymes and therefore is widely used as a solidifying agent for bacterial culture media. It is used as a laxative because of its great increase in bulk on absorption of water. It is also used by vegetarians when recipes call for gelatin.
2. A culture medium containing agar.
3. A constituent of dental hydrocolloid impression materials.