Oxoid CM0881B STAA琼脂培养基 STAA AGAR BASE 500G

Oxoid CM0881B STAA琼脂培养基 STAA AGAR BASE 500G

热杀索丝菌分离培养基

用于从食品中分离热杀索丝菌,由CM0881B与SR0151E组成STAA琼脂,配方符合ISO 13722:1996肉类制品中的微生物检测方法,CM0881B与SR0162E组成STA琼脂,符合Nordic Committee on Food Analysis (NMKL)方法。

货号 产品描述 规格 可配制培养基
CM0881B STAA琼脂基础/STA琼脂基础
STAA/STA Agar Base
500g 13.5L
SR0151E STAA选择性添加剂
STAA Selective Supplement,含放线菌酮
10小瓶 每小瓶500ml
SR0162E STA选择性添加剂
STA Selective Supplement,不含放线菌酮
10小瓶 每小瓶500ml

STAA琼脂基础/STA琼脂基础 CM0881:

配方表:

 成分*  含量 g/L
 蛋白胨  20.0
 酵母粉  2.0
 磷酸氢二钾  1.0
 硫酸镁  1.0
 琼脂  13.0
 pH 7.0±0.2 @25℃

*可根据标准需要自行调整配方

STAA选择性添加剂 SR0151E

 成分  每瓶SR0151E含量  每升培养基含量
 硫酸链霉素  250.0mg  500.0mg
 乙酸亚铊  25.0mg  50.0mg
 放线菌酮  25.0mg  50.0mg

STA选择性添加剂 SR0162E

 成分  每瓶SR0151E含量  每升培养基含量
 硫酸链霉素  250.0mg  500.0mg
 乙酸亚铊  25.0mg  50.0mg

使用方法:

称取18.5g的CM0881干粉到500ml蒸馏水中,轻轻搅拌加热煮沸至完全溶解,加入7.5ml甘油,121℃灭菌15分钟,冷却到50℃,加入1瓶SR0151E或SR0162E,混匀倒平板。

Dehydrated Culture Media

STAA AGAR BASE

CODE: CM0881

A medium for the isolation of Brochothrix thermosphacta from food samples.

Typical Formula*

gm/litre

Peptone

20.0

Yeast extract

2.0

Dipotassium hydrogen phosphate

1.0

Magnesium sulphate

1.0

Agar

13.0

pH 7.0 ± 0.2 @ 25°C
* Adjusted as required to meet performance standards

STAA Selective Supplement

Code: SR0151

Vial contents: (each vial is sufficient for 500ml of medium)
per vial
per litre
Streptomycin sulphate
250.0mg

500.0mg

Thallous acetate
25.0mg

50.0mg

Cycloheximide
25.0mg

50.0mg

STA Selective Supplement

Code: SR0162

Vial contents: (each vial is sufficient for 500ml of medium)
per vial
per litre
Streptomycin sulphate
250.0mg

500.0mg

Thallous acetate
25.0mg

50.0mg

Directions
Suspend 18.5g of STAA Agar Base in 500ml distilled water and bring gently to the boil to dissolve completely. Add 7.5g of glycerol and sterilise by autoclaving at 121° C for 15 minutes. Cool to 50°C and aseptically add:
a) for STAA Medium the contents of 1 vial of STAA Selective Supplement SR0151 reconstituted as directed.
b) for STA Medium the contents of 1 vial of STA Selective Supplement SR0162 reconstituted as directed.
Mix well and distribute into sterile Petri dishes.

Description
STAA Medium CM0881+ SR0151 is based on the formulation described by Gardner2 and is recommended for the microbiological examination of meat and meat products in the ISO Standard 13722:1996. When made up as STA Medium CM0881+SR0162 it complies with the method described by the Nordic Committee on Food Analysis (NMKL)3.

Brochothrix thermosphacta is a Gram-positive, non-motile, facultatively anaerobic rod-shaped micro-organism which occurs singly, in short chains or in long filamentous-like chains. It constitutes a significant proportion of the spoilage flora of meat and meat products stored aerobically or vacuum packed at chill temperatures, and is occasionally the dominant organism. It is, therefore, responsible for some of the off-odours which signal the onset of spoilage in vacuum packed meat products.

Although Brochothrix thermosphacta is not considered to be pathogenic, it is an economically important meat-spoilage organism because it grows in a wide variety of meats and meat products and produces malodorous metabolic end products which make affected meat unpalatable1.
STAA Medium is made selective by the inclusion of streptomycin sulphate, thallous acetate and actidione (cycloheximide). STA Medium is modified from the original formulation by removal of the toxic selective agent cycloheximide as recommended by the NMKL. According to this method the medium is applicable for meat, meat products and some fish products.

Streptomycin sulphate inhibits some Gram-positive organisms and most Gram-negatives at higher concentrations, whilst Brochothrix thermosphacta remains resistant. Thallous acetate inhibits most yeasts as well as many aerobic and facultatively anaerobic bacteria. The incorporation of cycloheximide serves to further inhibit yeasts and filamentous fungi.

Technique
Homogenise the test sample in sterile 0.1% peptone water or Maximum Recovery Diluent CM0733 and prepare appropriate dilutions. Transfer 0.1ml volumes to the agar plate and spread across the surface. Incubate at 22°C for 48 hours aerobically. Typical colonies of Brochothrix thermosphacta will grow as straw coloured colonies, 0.5-1.0mm in diameter. Pseudomonads able to grow on STAA and STA Media may be differentiated from Brochothrix thermosphacta by performing an oxidase test using Oxoid Oxidase Touch Sticks BR0064. Pseudomonads are oxidase positive.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the selective supplement in the dark at 2-8°C and use before the expiry date on the label.
The prepared medium may be stored for up to 2 weeks at 2-8°C.

Appearance
Dehydrated medium: Straw coloured free flowing powder
Prepared medium: Staw coloured gel

Quality control

Positive control: Expected results
Brochothrix thermosphacta ATCC® 11509* Good growth straw colonies
Negative control:
Staphylococcus aureus ATCC® 25923* No growth
This organism is available as a Culti-Loop®.

Precautions
STAA Selective Supplement SR0151 contains cycloheximide and thallous acatate and is toxic if swallowed, inhaled or if in contact with skin.
STA Selective Supplement SR0162 contains thallous acatate and is toxic if swallowed, inhaled or if in contact with skin.

References
1.Sneath, P.H.A and D. Jones (1986) Genus Brochothrix. In: Bergey’s Manual of Systematic Bacteriology, Vol.2, pp.1249-1253. Sneath, P.H.A., Mair, N.S. et al. (eds.). Williams & Wilkins, Baltimore.
2.Gardner,G.A.(1966)J. Appl. Bacteriol29 (3), 455-460.
3.Nordic Committee on Food Analysis: Brochothrix thermosphacta. Determination in Meat and Meat Products, No.141, 1991.

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