Oxford Modified Agar Base
A base medium, with the addition of antimicrobial agents, is used to promote the selective cultivation and isolation of Listeria spp.Purpose
This is a selective and differential culture medium which contains appropriated nutrients for an adequate bacterial growth.It is differential for the growing of Listeria spp., due to the product of esculin hydrolysis reacts with Fe3+ ions and a black coloured phenolic compound is produced. Selectivity is obtained by the addition of “Oxford Modified Agar Base, Selective Supplement”, because it contains antimicrobial agents which inhibit totally or partially the growth of the accompanying flora allowing the isolation of Listeria spp.
Formula (in grams per liter)
Instructions
Columbia Agar Base
39.0
Suspend 26.3 g in 500 ml of distilled water. Let it stand for 5 minutes Mix well. Heat with frequent agitation, and boil to dissolve completely. Dispense into containers and sterilize by autoclaving at 121°C for 15 minutes.Cool to 50 °C and aseptically add the content of 1 vial of Oxford Modified Selective Supplement, reconstituted according to instructions. Mix well and pour into sterile Petri dishes
Esculin
1.0
Iron ammonium citrate Lithium chloride pH: 7.2 ± 0.2
Inoculation
Directly, streak on the surface of the agarIncubation
At 35-37 ºC, for 24-48 hours in atmosphere with 5-10% % CO2Results
Listeria monocytogenes ATCC 19114 Small black colonies, with black haloes against amber background Listeria ivanovii ATCC 19119 Small black colonies, with black haloes against amber background Escherichia coli ATCC 25922 Enterococcus faecalis ATCC 29212 Appearance
Dehydrated medium: beige, free flowing, homogeneous powder.Prepared medium: amber coloured gel.
Storage:
Dehydrated medium: at 10-35 ºC.
Prepared medium: at 2-8 ºC.
Packaging
x 100g :Code: B02-235-05
x 500g :Code: B02-235-06