Product number: NCM2015

Xylose Lysine Deoxycholate (XLD) Agar is a selective agar for the detection of Salmonella spp.

Originally formulated by Taylor to differentiate enteric pathogens, the agar is widely used as the preferred differential medium for Salmonella spp. The medium is void of peptones but instead uses yeast extract as a carbon, nitrogen and vitamin source and xylose, lactose and sucrose are fermentable carbohydrates. Salmonella are able to ferment xylose to produce acid but not lactose or sucrose. When the xylose is exhausted Salmonella will decarboxylate lysine shifting the pH back to neutral. At near neutral pH, Salmonella can reduce sodium thiosulfate producing hydrogen sulfide which creates a complex with ferric ammonium citrate to produce black or black centered colonies. Other organisms are able decarboxylate lysine but acid production from the fermentation of lactose and sucrose keeps the pH too acidic for H2S production. Selectivity is achieved through the incorporation of sodium deoxycholate and phenol red acts as a pH indicator.

 

Formula Liter
Yeast Extract 3.0 g/L
Sodium Chloride 5.0 g/L
Xylose 3.75 g/L
Lactose 7.5 g/L
Sucrose 7.5 g/L
L-Lysine Hydrochloride 5.0 g/L
Sodium Thiosulfate 6.8 g/L
Ferric Ammonium Citrate 0.8 g/L
Phenol Red 0.08 g/L
Sodium Deoxycholate 1.0 g/L
Agar 13.0 g/L

Final pH: 7.4 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.

Preparation

  1. Suspend 53.5 grams of the medium in one liter of purified water.
  2. Bring rapidly to the boil with frequent stirring, and immediately transfer to a 45-50°C water bath. DO NOT OVERHEAT.
  3. Pour into plates as soon as the medium has cooled.
  4. Protracted boiling or prolonged holding at elevated temperature induces precipitation.

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Order Details

Product # Product Description
NCM2015A Xylose Lysine Deoxycholate (XLD) Agar CE, 500 g
NCM2015B Xylose Lysine Deoxycholate (XLD) Agar CE, 5 kg
NCM2015C Xylose Lysine Deoxycholate (XLD) Agar CE, 10 kg
NCM2015D Xylose Lysine Deoxycholate (XLD) Agar CE, 25 kg (European only size)

Reference Material

NCM2015 - Xylose Lysine Deoxycholate (XLD) Agar CE, Safety Data Sheet [Danish] [Dutch] [English] [EU English] [Finnish] [French] [German] [Hungarian] [Italian] [Spanish, Mexico] [Swedish]
NCM2015 - Xylose Lysine Deoxycholate (XLD) Agar CE, Technical Specifications Sheet [English]

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