Agar, or agar-agar, is widely used as a culture medium for growing micro-organisms. The stuff itself is also the product of micro-organisms.
Agar, or agar-agar, is widely used as a culture medium for growing micro-organisms. The stuff itself is also the product of micro-organisms.
Dissolving and cooling
Agar-agar means ‘jelly’ in the Malay language. It is a whitish substance without taste or colour produced from the cell walls of certain red algae. If you dissolve agar in hot water and then allow it to cool, it becomes a kind of jelly. This is used as a culture medium in a petri dish for growing micro-organisms such as fungi and bacteria.
Optimal growing temperature
Agar melts far less quickly than normal gelatine. This means that the petri dishes can be heated to the optimal growing temperature for micro-organisms without the agar melting. This temperature is around 37°C for most micro-organisms, the same temperature of the human body.
Binding and laxative
Agar has other uses besides that of a culture medium for micro-organisms. For example, it is used to thicken soup, as a laxative and as a food ingredient, for instance, in the Japanese dessert anmitsu. Agar even has its own E number (E406).