What is the role of Agar

• Agar is a solidifying agent.
• Agar is phycocolloid.
• Water soluble polysacharide.
• Extracted from red purple-marine algae (Rhodophyta).
• Including “ Gelidium” and “Gracillaria.”
•       Agar is a jelly-like substance.
•      Agar was  first used in microbiology in 1882 by the German microbiologist Walther Hesse, as assistant working in Robert Koch's laboratory. 
•      He discovered that it was more useful as a solidifying agent.

    Used For:

1.       Solidifying agent  -  1 to 2 % agar is used
2.       Growth of Anaerobes  - 0.1 % agar is used
3.       Motility studies - 0.05 to 0.5 % agar is used

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•  Obtained from seaweeds.
• Used for preparing solid medium.
• Remaining firm at temperature as high 65⁰C.
• Agar melts at approximate at 85⁰C.
• Agar melts at 85⁰C and sets at 45⁰C.
•      When agar used in formula, use agar that has a moisture content not more than 15% .
•      It has no nutrient value in media.
•      It was bacteriological inert(Not effected by the growth of the bacteria and fungi).
•      It is stable at different temperature used for incubation.
•      1-2% agar is  employed in solid medium.