ONE Broth - Listeria: Typical Formulation

• Peptone: 26g/L; Carbohydrate mix: 6g/L; Salt mix: 10g/L with a final pH of 7.4 ±0.2 at 25°C

Appearance:

• Dehydrated medium: straw coloured, free-flowing powder
• Selective supplement: orange/yellow, freeze-dried pellet
• Prepared medium: dark straw coloured, clear liquid

Note:

Formulation Directions

• Suspend 22g of ONE Broth-Listeria Base in 500mL (44g/L) of distilled water
• Mix well and sterilize by autoclaving at 121°C for 15 minutes
• Cool the medium to below 50°C and aseptically add the contents of one vial of ONE Broth-Listeria Selective Supplement (Mfr. No. SR0234) reconstituted as directed

Testing Protocol

• Add 25g of food sample to 225mL of ONE Broth-Listeria and stomach for a minimum of 30 seconds to mix the sample
• Incubate the broth without agitation at 30°C for 24±2 hours

Gently agitate the bag then, using a microbiological loop, remove 10μL and inoculate onto a suitable agar medium e.g. Brilliance Listeria Agar (Mfr. No. CM1080, SR0222, and SR0228) and incubate appropriately (37°C for 24-48 hours)

• Confirm presumptive colonies on the agar plates as Listeria monocytogenes or Listeria spp. by appropriate methods e.g. Gram-stain, catalase, oxidase, Oxoid Listeria Latex Test Kit (Mfr. No. DR1126)
• Oxoid O.B.I.S. mono (Mfr. No. ID0600), Microbact Listeria 12L (Mfr. No. MB1128)