Oxoid CM0906R R2A琼脂 R2A AGAR

Oxoid CM0906R R2A琼脂 R2A AGAR

Dehydrated Culture Media

R2A AGAR

Code: CM0906

A medium for the bacterial examination of drinking water.

用于饮用水细菌检查的培养基。

Typical Formula*

gm/litre

Yeast extract

0.5

Proteose peptone

0.5

Casein hydrolysate

0.5

Glucose

0.5

Starch

0.5

Di-potassium phosphate

0.3

Magnesium sulphate

0.024

Sodium pyruvate

0.3

Agar

15.0

pH 7.2 ± 0.2 @ 25°C
* Adjusted as required to meet performance standards

Directions
Suspend 18.1g in 1 litre of distilled water. Bring to the boil to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes. Mix well and pour into sterile Petri dishes.

方向
将 18.1 克悬浮在 1 升蒸馏水中。 煮沸以完全溶解。 通过在 121°C 高压灭菌 15 分钟进行灭菌。 充分混合并倒入无菌培养皿中。

Description
Standard methods for the enumeration of heterotrophic bacteria in water have traditionally used nutritionally rich media, such as Plate Count Agar, with incubation at 35°C1. Organisms isolated under these conditions may represent only a small percentage of the bacteria present in the sample2.

R2A Agar developed by Reasoner and Geldreich2 is a nutritionally reduced medium. It was demonstrated that using this medium and incubating for longer at lower temperatures enhanced the recovery of stressed and chlorine damaged bacteria from treated waters resulting in higher, more realistic bacterial counts.

描述
计数水中异养细菌的标准方法传统上使用营养丰富的培养基,例如平板计数琼脂,在 35°C 下孵育。 在这些条件下分离的生物可能仅代表样本中存在的一小部分细菌2。

由 Reasoner 和 Geldreich2 开发的 R2A 琼脂是一种营养减少的培养基。 结果表明,使用这种培养基并在较低温度下孵育更长时间,可以提高处理过的水中受胁迫和氯损伤的细菌的回收率,从而产生更高、更真实的细菌计数。



Technique
R2A Agar may be used in poured plate, spread plate and membrane filtration procedures. Refer to standard methods for sample collection and testing1,2,4 .

Recommended incubation is for 5-7 days at 20°C or 28°C, or for 3 days at 35°C.

Storage conditions and Shelf life
R2A Agar should be stored tightly capped in the original container at 10-30°C. When stored as directed the medium will remain stable until the expiry date printed on the label.

The prepared medium may be stored for up to 2 weeks at 2-8°C.

Appearance
Dehydrated medium: Pale straw coloured, free-flowing powder
Prepared medium: Light straw coloured gel

Quality control

Positive control: Expected results
Staphylococcus aureus ATCC® 6538 * Good growth; white coloured colonies
Negative control:
Uninoculated medium No change
* This organism is available as a Culti-Loop®

References
1. Greenbreg, Trussell and Clesceri (ed) (1998) Standard Methods for the Examination of Drinking Water and Waste Water. 20th Ed. APHA,
Washington DC.
2. Reasoner and Geldreich (1985). Appl. Environ. Microbiol. 49, 1.
3. Environment Agency- The Microbiology of Drinking Water 2002
4. European Pharmacopoeia 2002, supplement 4.6.

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