HiCrome™ Coliform Agar (Coliform Agar, HiCrome™)

[所属分类:培养基配方] [发布时间:2021-4-7] [发布人: ] [阅读次数:] [返回]

HiCrome™ Coliform Agar

(Coliform Agar, HiCrome™)

培养基配方

Composition per liter:
Agar............................................................................................12.0g
Sodium chloride............................................................................5.0g
Peptone, special ............................................................................3.0g
K 2 HPO 4 .........................................................................................3.0g
KH 2 PO 4 .........................................................................................1.7g
Sodium pyruvate...........................................................................1.0g
Tryptophan....................................................................................1.0g
Chromogenic mixture...................................................................0.2g
Sodium lauryl sulphate.................................................................0.1g
pH 6.8 ± 0.2 at 25°C
Source: This medium is available as a premixed powder from HiMedia.
Preparation of Medium: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat while stirring and bring to boiling. Autoclave for 15 min at 15 psi pressure–121°C. Pour into sterile Petri dishes.
Use: For the simultaneous detection of Escherichia coli and total coliforms in water and food samples. Sodium lauryl sulphate inhibits Gram-positive organisms. The chromogenic mixture contains two chromogenic substrates as Salmon-GAL and X-glucuronide. The enzyme β- D -galactosidase produced by coliforms cleaves Salmon-GAL, resulting in the salmon to red coloration of coliform colonies. The enzyme β- D -glucuronidase produced by E. coli cleaves X-glucuronide. Escherichia coli forms dark blue to violet coloued colonies due to cleavage of both Salmon-GAL and X-glucuronide. The addition of tryptophan improves the indole reaction, thereby increasing detection reliability in combination with the two chromogens.