Definition

1. Noun:
   • A gelatinous substance derived from algae: A colloidal extract obtained from certain types of red algae, primarily used to solidify culture media for growing microorganisms and as a thickening or gelling agent in various food products.
   • A culture medium solidified with this substance: Refers to any nutrient medium used in laboratories for cultivating bacteria, fungi, or other cells, which has been solidified using agar.

Usage Examples

• Noun:
  • The scientist prepared petri dishes containing nutrient agar to grow the bacterial samples.
  • Agar is a common vegetarian substitute for gelatin in many desserts.

Advanced Usage

• "Agar plate": A sterile petri dish containing a growth medium solidified with agar, used for culturing microorganisms.

  • The technician streaked the specimen onto an agar plate to isolate individual colonies.

• "Agarose": A purified linear polysaccharide derived from agar, used extensively in gel electrophoresis for separating DNA fragments.

  • The researcher poured an agarose gel to analyze the PCR products.

Variants and Related Words

• Agar-agar (n): An alternative full name for agar, emphasizing its algal origin.
  • The recipe called for agar-agar to set the vegan panna cotta.

Synonyms

• Culture medium (when referring to the gelled growth substrate).
• Gelling agent (in the context of food science).
• Phytocolloid (a technical term for plant-derived gelling substances).

Notes on Meaning

• The primary meaning relates to its role in science as a solidifying agent for microbiological media. Its property of being indigestible to most microbes makes it ideal for this purpose.
• Its secondary meaning is as a food additive (E406), valued for its vegetarian, vegan, and kosher status compared to animal-based gelatin.

Noun

1. a colloidal extract of algae; used especially in culture media and as a gelling agent in foods
2. any culture medium that uses agar as the gelling agent