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Chromogenic E. coli/Coliform Medium

[所属分类:培养基配方] [发布时间:2021-11-12] [发布人:网站管理员2] [阅读次数:] [返回]

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

Composition per liter:

Chromogenic mix .............................................20.3g

Agar ..................................................................15.0g

Peptone ...............................................................5.0g

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

Na2HPO4.............................................................3.5g

Yeast extract........................................................3.0g

Lactose................................................................2.5g

NaH2PO4.............................................................1.5g

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

pH 6.8 ± 0.2 at 25°C

Preparation of Medium: Add components to dis

tilled/deionized water and bring volume to 1.0L. Mix

thoroughly. Gently heat and bring to boiling. Dispense

into tubes or flasks. Autoclave for 15 min at 15 psi

pressure–121°C. Pour into sterile Petri dishes or leave

in tubes.

Use: For the differentiation between Escherichia

coli and other coliforms in cultures produced from

food samples. Agar base uses two enzyme substrates

to differentiate between E. coli and other coliforms.

One chromogenic substrate is cleaved by the enzyme

glucuronidase which is specific for E. coli and pro

duced by approximately 97% of strains. The second

chromogenic substrate is cleaved by galactosidase,

an enzyme produced by the majority of coliforms.

This results in purple E. coli colonies, as they are able

to cleave both chromogenic substrates and pink

coliform colonies as they are only able to cleave the

galactosidase chromogen.