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Rainbow Agar O157

[所属分类:培养基配方] [发布时间:2021-12-13] [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

pH 7.9–8.3 at 25°C

Source: This medium is available from Biolog.

Preparation of Medium: Add components to

distilled/deionized water and bring volume to 1.0L.

Mix thoroughly. Gently heat and boil to dissolve

components. Autoclave for 10 min at 15 psi pres

sure–121°C. Do not exceed 10 min at this tempera

ture and pressure. For volumes less than 500.0mL,

autoclave for 5 min. Cool agar to 45-50°C before

pouring plates or adding selective agents.To increase

the selectivity of this medium, add a sterile solution

of 0.8 mg/L potassium tellurite and 10.0 mg/L novo

biocin. Tellurite is highly selective for E. coli

O157:H7 and will reduce background flora consider

ably. Novobiocin inhibits Proteus swarming and the

growth of tellurite-reducing bacteria.

Use: As a selective, chromogenic culture medium to

aid in the detection, isolation, and presumptive iden

tification of verotoxin-producing strains of Escheri

chia coli, particularly serotype O157:H7. The medi

um contains chromogenic substrates that are specific

for two E. coli-associated enzymes: β-galactosidase

(a blue-black chromogenic substrate) and β-glucu

ronidase (a red chromogenic substrate). Strain

O157:H7 is typically glucuronidase negative so it

forms unique and distinctive black or gray colonies.

Many other non-O157 toxigenic strains overproduce

β-galactosidase relative to β-glucuronidase on this

medium and consequently they are typically colored

purple, violet, or blue. Most non-pathogenic E. coli

strains are glucuronidase positive, and range from

pink to magenta with occasional purple or blue

strains. Nearly all other bacterial species are either

inhibited on this medium or they grow as white or

cream-colored colonies.