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HiCrome MacConkey-Sorbitol Agar MacConkey-Sorbitol Agar, HiCrome

[所属分类:培养基配方] [发布时间:2021-11-23] [发布人:网站管理员2] [阅读次数:] [返回]

HiCrome MacConkey-Sorbitol Agar

MacConkey-Sorbitol Agar, HiCrome

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

Composition per liter:

Casein enzymic hydrolysate .............................17.0g

Agar ..................................................................13.5g

Sorbitol .............................................................10.0g

NaCl....................................................................5.0g

Proteose peptone.................................................3.0g

Bile salts mixture ................................................1.5g

5-Bromo-4-chloro-3-indolyl-β-D-glucuronide

sodium salt....................................................0.1g

Neutral Red.......................................................0.03g

Crystal Violet..................................................0.001g

pH 7.1 ± 0.3 at 25°C

Source: This medium is available from Fluka, Sig

ma-Aldrich.

Preparation of Medium: Add components to

distilled/deionized water and bring volume to 1.0L.

Mix thoroughly. Gently heat while stirring and bring

to boiling. Mix to completely dissolve components.

Do not autoclave. Cool to 50°C. Pour into sterile Pet

ri dishes.

Use: For the direct isolation and differentiation of E.

coli O157:H7-strains from foodstuffs. Recommend

ed for selective isolation of Escherichia coli

O157:H7 from food and animal feeding stuffs. The

medium contains sorbitol instead of lactose. Entero

pathogenic strains of Escherichia coli O157:H7 fer

ment lactose but do not ferment sorbitol and hence

produce colorless colonies. Sorbitol fermenting

strains of Escherichia coli produce pink-red colo

nies. The red color is due to production of acid from

sorbitol, absorption of neutral red, and a subsequent

color change of the dye when pH of the medium falls

below 6.8. The chromogenic indicator is added to de

tect the presence of an enzyme β-D-glucuronidase.

Strains of Escherichia coli possessing β-D-glucu

ronidase appear as blue colored colonies on the me

dium. Enteropathogenic strains of Escherichia coli

O157 do not possess β-D-glucuronidase activity and

thus produce colorless colonies. Escherichia coli fer

menting sorbitol and possessing β-D-glucuronidase

activity produce purple colored colonies. Most of the

gram-positive organisms are inhibited by crystal vio

let and bile salts.

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HiCrome MacConkey-Sorbitol Agar MacConkey-Sorbitol Agar, HiCrome