Buffered Listeria Enrichment Broth

LAB 139

Description

A medium for the selective enrichment of food and environmental samples for Listeria spp, LAB 139 is a buffered version of the ‘FDA' broth LAB 138. The extra buffering capacity maintains the pH of the enrichment culture during incubation, ensuring optimum conditions for the recovery of Listeria spp.

Method for reconstitution

Weigh 47 grams of powder and add to 1 litre of deionised water. Allow to soak for 10 minutes then swirl to mix and sterilise by autoclaving at 121˚C for 15 minutes. Cool to 47˚C and add 2 vials of X138 (X139/X539 can be used as an alternative) reconstituted in 50% alcohol. Aseptically dispense into sterile tubes or bottles.

Appearance: Yellow, clear.

pH: 7.2 ± 0.2

Minimum Q.C. organisms: L. monocytogenes NCIMB 50007 E. coli (inhibition) NCIMB 50034

Storage of Prepared Medium: Capped containers - up to 14 days at 2-8˚C in the dark.

Inoculation: Add 25 grams of sample to 225mls of Buffered Listeria Enrichment Broth and homogenise.

Incubation: 30˚C aerobically for up to 48 hours.

Subculture: After 24 and 48 hours onto Listeria Isolation Medium - LAB 122.