Rainbow Agar O157

[所属分类:培养基配方] [发布时间:2021-8-2] [发布人:网站管理员2] [阅读次数:] [返回]

Rainbow Agar O157

山东拓普生物工程有限公司 培养基配方 http://www.topbiol.com

Composition per liter:

Proprietary.
Source:  This medium is available as a premixed powder from Biolog
Inc.
Preparation:  Suspend 60.0g of the proprietary mixture in distilled/
deionized water and bring volume to 1.0L. Mix thoroughly. Gently
heat and bring to boiling. Autoclave for 15 min at 15 psi pressure–
121°C. Cool to 45°C–50°C. Mix thoroughly. Pour into sterile Petri
dishes or distribute into sterile tubes. The final medium should be clear
and virtually colorless. No pH adjustment is needed. The final pH
should be pH 7.9–8.3. To increase the selectivity of the medium, a ster-
ile solution containing 0.8mg potassium tellurite and 10mg novobiocin
can be added. Caution must be used because tellurite is toxic.
Use : For the detection, isolation, and presumptive identification of
verotoxin-producing strains of Escherichia coli, particularly serotype
O157:H7. The medium contains chromogenic substrates that are spe-
cific for two E. coli-associated enzymes: β-galactosidase (a blue-black
chromogenic substrate) and β-glucuronidase (a red chromogenic sub-
strate). The distinctive black or gray coloration of E. coli O157:H7 col-
onies is easily viewed by laying the Petri plate against a white back-
ground. When O157 is surrounded by pink or magenta non-toxigenic
colonies, it may have a bluish hue. The addition of selective agents
improves performance. E. coli O157:H7 colony coloration will be
slightly bluer with these selective agents added. Tellurite is highly
selective for E. coli O157:H7 and can reduce background flora consid-
erably. Novobiocin inhibits Proteus swarming and the growth of tellu-
rite-reducing bacteria. Rare strains of O157:H7 are tellurite sensitive.