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In this section: Laboratory Methods (Food)

BAM Media M40: Christensen's Urea Agar

January 2001

Base

Peptone	1 g
NaCl	5 g
Dextrose	1 g
KH₂PO₄	2 g
Phenol red (6 ml of 1:500 solution)	0.012 g
Agar	15 g
Distilled water	900 ml

Dissolve all ingredients except urea in 900 ml water (basal medium).

For halophilic Vibrio spp., add extra 15 g NaCl (final NaCl concentration, 2%).

Autoclave 15 min at 121°C. Cool to 50-55°C.

Urea concentrate

Urea	20 g
Distilled water	100 ml

Dissolve urea in 100 ml water.

Filter-sterilize; add aseptically to cooled basal medium. Mix. Final pH, 6.8 ± 0.1. Dispense to sterile tubes or petri dishes. Slant tubes for 2 cm butt and 3 cm slant.

Original Source: Bacteriological Analytical Manual, 8th Edition, Revision A, 1998.

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