培养基配方

您现在的位置：网站首页 >> 培养基配方

Chromogenic Enterobacter sakazakii Agar, DFI Formulation

[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]

Chromogenic Enterobacter sakazakii

Agar, DFI Formulation

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

Composition per liter:

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

Tryptone............................................................15.0g

Soya peptone.......................................................5.0g

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

Ferric ammonium citrate.....................................1.0g

Sodium deoxycholate.........................................1.0g

Na2S2O3 ..............................................................1.0g

Chromogen..........................................................0.1g

pH 7.3 ± 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. Allow tubes to cool in a slanted position.

Use: For the differentiation and enumeration of En

terobacter sakazakii from infant formula and other

food samples. The enzyme α-glucosidase, present in

E. sakazakii, hydrolyzes the substrate 5-bromo-4-

chloro-3-indolyl-α,D-glucopyranoside, thus produc

ing blue-green colonies on this pale yellow medium.

Proteus vulgaris is also weakly α-glucosidase posi

tive and could grow to give colonies of a similar col

or to E. sakazakii. However, on this medium, Proteus

spp. grow as grey colonies: they produce hydrogen

sulphide in the presence of ferric ions forming fer

rous sulphide. Deoxycholate inhibits the growth of

most Gram-positive organisms.