Oxoid培养基 CM0079B Oxoid 亚硫酸铁琼脂(Iron Sulphite Agar)

Oxoid培养基 CM0079B Oxoid 亚硫酸铁琼脂(Iron Sulphite Agar)

Dehydrated Culture Media

IRON SULPHITE AGAR

Code: CM0079

A medium for the detection of thermophilic anaerobic organisms.

用于检测嗜热厌氧生物的培养基。

Typical Formula*

gm/litre

Tryptone

10.0

Sodium sulphite

0.5

Iron (III) citrate

0.5

Agar

12.0

pH 7.1 ± 0.2 @ 25°C
* Adjusted as required to meet performance standards

Directions
Suspend 23.0g in 1 litre of distilled water and boil to dissolve completely. Sterilise by autoclaving for 15 minutes at 121°C. Mix well before pouring.

Description
This medium is a modification of Cameron Sulphite Agar developed by the National Canners Association of America 1.

It had been shown that the medium was improved by reducing the concentration of sodium sulphite. Beerens 2 showed that some strains of Clostridium sporogenes would not tolerate 0.1% sulphite. This was confirmed by Mossel et al.3 who consequently used iron sulphite agar containing only 0.05% sulphite and obtained no apparent inhibition.

Technique
Iron Sulphite Agar is particularly suitable for the detection of thermophilic anaerobic organisms causing sulphide spoilage in food. The medium should be dispensed in 10ml amounts in tubes for deepshake cultures, and inoculated whilst fluid at about 50°C. Allow to set and incubate at 55°C for thermophilic species. Desulfotomaculum nigrificans, the type species, produces distinct black spherical growths in the depth of the medium.
In the Attenborough and Scarr method 4, diluted samples of the sugar were filtered through membrane filters which were then rolled up and placed in tubes containing enough melted Iron Sulphite Agar (at approximately 50°C) to cover them. The medium was allowed to solidify and the tubes were incubated at 56°C. After 48 hours the number of black colonies on the membrane was counted. This membrane filter technique is quicker than the standard method but of comparable accuracy, and permits the examination of a much larger sample 5.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium below 25°C.

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

方向
将 23.0g 悬浮在 1 升蒸馏水中,煮沸至完全溶解。在 121°C 高压灭菌 15 分钟进行灭菌。倒入前充分混合。

描述
该培养基是由美国国家罐头协会 1 开发的 Cameron Sulphite Agar 的改良版。

已经表明,通过降低亚硫酸钠的浓度可以改善培养基。 Beerens 2 表明,某些产孢梭菌菌株不能耐受 0.1% 的亚硫酸盐。 Mossel 等人 3 证实了这一点,他们因此使用了仅含有 0.05% 亚硫酸盐的亚硫酸铁琼脂,并且没有获得明显的抑制作用。

技术
亚硫酸铁琼脂特别适用于检测导致食品中硫化物变质的嗜热厌氧微生物。培养基应以 10ml 的量分装在用于深摇培养的试管中,并在约 50°C 的液体中接种。对于嗜热物种,允许在 55°C 下设置和孵育。 Desulfotomaculum nigrificans,模式物种,在培养基深处产生明显的黑色球形生长。
在 Attenborough 和 Scarr 方法 4 中,稀释的糖样品通过膜过滤器进行过滤,然后将膜过滤器卷起并放入装有足够熔化的亚硫酸铁琼脂(约 50°C)以覆盖它们的管中。使培养基固化并将试管在56°C温育。 48小时后计数膜上的黑色菌落数。这种膜过滤技术比标准方法更快,但具有相当的准确性,并且允许检查更大的样品 5。

储存条件和保质期
将脱水培养基储存在 10-30°C 并在标签上的有效期之前使用。
将准备好的培养基储存在 25°C 以下。

外貌
脱水介质:浅稻草色、自由流动的粉末
制备培养基:稻草灰色凝胶

Quality Control

Positive controls: Expected results
Clostridium sporogenes ATCC® 19404* Good growth; blackening
Desulfotomaculum nigrificans ATCC® 19858 Good growth; blackening
Negative control:
Escherichia coli ATCC® 25922* Good growth; no blackening
* This organism is available as a Culti-Loop®

Precautions
The blackening reaction is only presumptive evidence of clostridial growth. Confirmation tests must be carried out to identify the organism growing in the medium.

References
1. Tanner F. W. (1944) `The Microbiology of Foods’ 2nd ed., Garrard Press, Illinois p. 1127.
2. Beerens H. (1958) DSIR, Proc. 2nd Internat. Symp. Food Microbiol. 1957, HMSO, London, pp. 235-245.
3. Mossel D. A. A., Golstein Brouwers G. W. M. V. and de Bruin A. S. (1959) J. Path. Bact. 78. 290-291.
4. Attenborough Sheila J. and Scarr M. Pamela (1957) J. Appl. Bact. 20. 460-466.
5. Bufton A. W. J. (1959) J. Appl. Bact. 22. 278-280.

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