Description
DESCRIPTION
Agar is a solidifying agent used for culture media preparation, it is a purified agar from which the extraneous matter, pigmented portions and salts have been removed or reduced to a minimum. It is an hydrosoluble extract from red algae and can be used as a solidifying agent in bacteriological culture media or for determining motility and growth of anaerobes and microaerophiles.
PREPARATION
Agar is typically used in a final concentration of 1-2% for solidifying culture media. Smaller quantities (0.05-0.5%) are used in media for motility studies (0.5%w/v), growth of anaerobes (0.1%) and microaerophiles. 1.5% aqueous solution supplies solid gel at temperature of 35 °C because agar does not melt at temperature lower than 85 °C. The addition of such amounts of agar to liquid media permits all degrees of oxygen tension to exist, thus aids in the development of many fastidious aerobic and anaerobic organisms.