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Minggu, 01 Mei 2011

EMB agar

EMD Cat. No. 1.01347.0500
500 g


Selective agar proposed by HOLT-HARRIS and TEAGUE (1916) for the detection and isolation of pathogenic Enterobacteriaceae.


Mode of Action Preparation
Experimental Procedure and Evaluation Quality Control
Typical Composition (g/liter) Literature
Picture/Image




Mode of Action The lactose and sucrose contained in this medium allow lactose- and sucrose-negative salmonellae and shigellae to be distinguished from lactose-positive coliform organisms and lactose-negative, sucrose-positive, accompanying flora (e.g. Proteus vulgaris, Citrobacter, Aeromonas hydrophila). The growth of undesired accompanying microorganisms, particularly Gram-positive bacteria, is largely inhibited by the dyes present in the medium.

Typical Composition (g/liter) Peptones 10.0; di-potassium hydrogen phosphate 2.0; lactose 5.0; sucrose 5.0; eosin Y, yellowish 0.4; methylene blue 0.07; agar-agar 13.5.

Preparation Suspend 36 g in 1 liter of purified water. Autoclave (15 min at 121°C), pour plates. pH: 7.1 ± 0.2 at 25°C. The plates are clear and reddish-brown to violet-brown.

Experimental Procedure and Evaluation Inoculate by spreading the sample material thinly on the surface of the plates. Incubation: 24 hours at 35°C aerobically.

Appearance of Colonies Microorganisms
Translucent, amber colored Salmonella, Shigella
Greenish, metallic sheen in reflected light, blue-black centre in transmitted light Escherichia coli
Colonies are larger than those of E. coli, mucoid, confluent, gray-brown centre in transmitted light Enterobacter, Klebsiella and others


Quality control

Test strains Growth Colony color Metallic sheen
Escherichia coli ATCC 25922 good / very good violet +
Escherichia coli ATC 11775 good / very good violet +
Escherichia coli 194 good / very good violet +
Escherichia coli ATCC 23716 good / very good violet +
Escherichia coli ATCC 8739 good / very good violet +
Enterobacter cloacae ATCC 13047 fair / very good pink, dark centre + / -
Salmonella typhimurium ATCC 14028 good / very good colorless, transparent -
Shigella flexneri ATCC 12022 good / very good colorless, transparent -
Bacillus cereus ATCC 11778 none / poor
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Literature

HOLT-HARRIS, J.E., a. TEAGUE, O.A.: A new culture medium for the isolation of Bacillus typhosus from stools. - J. Infect. Dis., 18; 596-600 (1916).

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