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Coliform Agar, Chromocult® (Chromocult Coliform Agar)

[所属分类:培养基配方] [发布时间:2021-11-12] [发布人:网站管理员2] [阅读次数:] [返回]

Coliform Agar, Chromocult®

(Chromocult Coliform Agar)

山东拓普生物工程有限公司培养基配方 http://www.topbiol.com

Composition per liter:

Agar ..................................................................10.0g

NaCl....................................................................5.0g

Peptone................................................................3.0g

Na2HPO4 .............................................................2.7g

NaH2PO4 .............................................................2.2g

Tryptophan..........................................................1.0g

Na-pyruvate ........................................................1.0g

Chromogenic mixture .........................................0.4g

Tergiotol 7.........................................................0.15g

pH 7.0 ± 0.2 at 25°C

Source: This medium is available from Merck.

Preparation of Medium: Add components to

distilled/deionized water and bring volume to 1.0L.

Mix well and warm gently until dissolved. Autoclave

for 15 min at 15 psi pressure–121°C. Pour into sterile

Petri dishes. Some turbidity may occur, but this does

not effect the performance

Use: For the detection of E. coli and coliform bacte

ria in foods. The interaction of selected peptones,

pyruvate, sorbitol, and phosphate buffer guarantees

rapid colony growth, even for sublethally injured

coliforms. The growth of Gram-positive bacteria as

well as some Gram-negative bacteria is largely inhib

ited by the content of Tergitol 7 which has no nega

tive effect on the growth of the coliform bacteria. A

combination of two chromogenic substrates which

allow for the simultaneous detection of total

coliforms and E. coli. The characteristic enzyme for

coliforms, β-D-cleaves the Salmon-GAL substrate

and causes a salmon to red color of the coliform col

onies. The substrate X-glucuronide is used for the

identification of β-D-glucuronidase, which is charac

teristic for E. coli. E. coli cleaves both Salmon-GAL

and X-glucuronide, so that positive colonies take on

a dark-blue to violet color. These are easily distin

guished from other coliform colonies which have a

salmon to red color. As part of an additional confir

mation of E. coli, the inclusion of tryptophan im

proves the indole reaction, thereby increasing detec

tion reliability when it is used in combination with

the Salmon-GAL and X-glucuronide reaction.

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Coliform Agar, Chromocult® (Chromocult Coliform Agar)