HiCrome™ Coliform Agar with Novobiocin (Coliform Agar with Novobiocin, 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 with Novobiocin

(Coliform Agar with Novobiocin, 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
Novobiocin.................................................................................5.0mg
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 when high numbers of Gram-positive bacteria may be present. Novobiocin and sodium lauryl sulphate inhibit 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 SalmonGAL, 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 colored 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.