Formula and principle of Congo Red medium

Cellulose Congo red medium was used to isolate and identify cellulose decomposing bacteria, and there was a red decomposition circle around cellulose decomposing bacteria.

The formula of the Congo red culture medium(http://www.hnhbsj.com):
Sodium nitrate 1.0
Disodium hydrogen phosphate 1. 2
Potassium dihydrogen phosphate 0.9
Magnesium sulfate 0.5]
Potassium chloride 0,5
Yeast extract powder 0.5
Acid hydrolyzed casein 0.5
Congo Red 0.2
Cellulose powder 5.0
Agar 15.0
PH value 7. 0 ±0. 25 ℃

Use of Congo Red medium(http://www.hnhbsj.com):
Weighing 25.3 g, heated and dissolved in 1000ml distilled water, divided, sterilized at 121 ℃ for 15 minutes, set aside.
The principle of screening bacteria in cellulose Congo red medium:
1. Congo red can combine firmly with macromolecular polysaccharides.
2. The cellulose is a macromolecular polysaccharide, which is firmly combined with the polysaccharide.
3Cellulase degrades cellulose in the plate into small molecular sugar, so Congo red can not bind to small molecule sugar, so it is eluted and appears transparent circle.
(4) in the normal cellulose Congo red culture medium, the bacteria were first cultured on a plate containing cellulose. After the bacteria were grown out, the bacteria were scraped off, then stained with Congo red for 10-15 minutes, then washed with NaCl for 2-3 times. It is the bacteria that hydrolyze cellulose that produce transparent loops. Congo red can also be added directly to the plate, the bacteria will gradually form a transparent circle during the growth process, but the method is more sensitive.

Cellulose Congo Red medium is the identification medium, because it can also grow other microorganisms, such as some autotrophic microorganisms can survive on the medium;! However, only around the cellulosic decomposition bacteria will form a transparent circle, which will identify the colony.