| Media - XLD Agar For the Identification of Bacteria |
XLD Agar: Click Here to View Images
XLD Agar (xylose-lysine-deoxycholate agar) is used in the selective
identification of the gram-negative Salmonella and Shigella Species.
Growth Characteristics:
XLD Agar is both a selective and differential media. XLD agar is inhibitory to
gram positive bacteria and is indicative of fermentation and hydrogen
sulfide production. It is selective because it contains deoxycholate which
inhibits gram positive bacteria from growing. It is differential, in that
species that can ferment the sugars xylose, sucrose, or lactose appear
yellow, while species such as Salmonella and Shigella, which cannot
ferment these sugars appear red. It is also differential, in that bacteria
which produce hydrogen sulfide (ie. Salmonella) appear black.
Typical Formulation per Liter:
XLD Agar (xylose-lysine-deoxycholate agar) is used in the selective
identification of the gram-negative Salmonella and Shigella Species.
Growth Characteristics:
XLD Agar is both a selective and differential media. XLD agar is inhibitory to
gram positive bacteria and is indicative of fermentation and hydrogen
sulfide production. It is selective because it contains deoxycholate which
inhibits gram positive bacteria from growing. It is differential, in that
species that can ferment the sugars xylose, sucrose, or lactose appear
yellow, while species such as Salmonella and Shigella, which cannot
ferment these sugars appear red. It is also differential, in that bacteria
which produce hydrogen sulfide (ie. Salmonella) appear black.
Typical Formulation per Liter:
- Yeast extract 3.0 g
- L-lysine 5.0 g
- Xylose 3.75 g
- Lactose 7.5 g
- Sucrose 7.5 g
- Sodium deoxycholate 1.0 g
- Sodium chloride 5.0 g
- Sodium thiosulfate 6.8 g
- Ferric ammonium citrate 0.8 mg
- Phenol red 0.08 g
- Agar 12.5 g
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