Appearance (Colour)
Biege with greyish tinge
Appearance (Form)
Free flowing, homogeneous powder
Solubility
34.56 gm/liter
Solubility before autoclaving (Clarity)
Clear to slightly opalescent
Gel strength
Firm, comparable with 1.5% agar gel
pH (25°C)
6.7 ± 0.2
Prepared Medium Appearance after autoclaving (Clarity)
Clear to slightly opalescent
Prepared Medium Appearance after autoclaving (Colour)
Purple
Cultural Response
Inoculate and incubate at 37°C for 18 - 24 hours
Organism
Escherichia coli ATCC 25922
Inoculum (cfu) 10-100
Growth Slant Butt H2S
Good K K -
Organism
Salmonella typhimurium ATCC 14028
Inoculum (cfu) 10-100
Growth Slant Butt H2S
Good K K +
Organism
Proteus mirabilis ATCC 25933
Inoculum (cfu) 10-100
Growth Slant Butt H2S
Good A R +
Organism
Shigella flexneri ATCC 12022
Inoculum (cfu) 10-100
Growth Slant Butt H2S
Good A K -
Key
A = acidic, yellow; K = alkaline, purple, no colour change; R = deep red, lysine deamination; H2S = (+) blackening of medium; H2S = (-) no blackening of medium.
Applications
For the differentiation of enteric organisms, especially Salmonella, based upon lysine decarboxylation/ deamination and H2S production.
Composition
Ingredients
gm/lt.
L-Lysine
10.00
Pancreatic digest of gelatin
5.00
Yeast extract
3.00
Dextrose
1.00
Ferric ammonium citrate
0.50
Sodium thiosulphate
0.04
Bromocresol Purple
0.02
Agar
15.00
Directions
1. Add 34.56 gm powder to distilled/purified water.
2. Bring volume to 1.0 litre and mix thoroughly.
3. Gently heat and bring to boiling.
4. Dispense into test tubes.
5. Autoclave at 15 psi pressure at 121°C for 15 minutes.
