Gassner Agar (Water-Blue Metachrome-Yellow Lactose Agar)

[所属分类:培养基配方] [发布时间:2021-3-8] [发布人: ] [阅读次数:] [返回]

培养基配方

Composition per liter:
Lactose........................................................................................43.0g
Peptone........................................................................................14.0g
Agar ............................................................................................13.0g
NaCl..............................................................................................5.0g
Metachrome Yellow....................................................................1.25g
Water Blue ..................................................................................0.62g
pH 7.2 ± 0.2 at 25°C
Preparation of Medium: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat and bring to boiling. Mix thoroughly. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure–121°C. Pour into sterile Petri dishes.
Use: For the detection and isolation of pathogenic Enterobacteriaceae. For use in the execution of the German Meat Inspection Law (Deutsches Fleischbeschaugesetz). This culture medium contains Metachrome Yellow, which primarily inhibits the accompanying Gram-positive microbial flora. It also contains lactose, which, when degraded to acid, is shown by the indicator Water Blue, which is deep blue in the acidic range and colorless in the alkaline range. The prepared culture medium is green; in the acidic pH range it becomes bluegreen to blue. At alkaline pHs, however, the yellow color of the Metachrome Yellow becomes increasingly apparent.