Agar Listeria Ottaviani Agossi(ALOA)

AL Medium (Agar Listeria according to Ottaviani and Agosti) is based on the simultaneous detection of two enzyme activities: β-glucosidase and phosphatidylinositol-specific phospholipase C (PI-PLC).

Key Benefits

• Detection of Listeria spp. in 24 hr after 24 hr of enrichment
• Only1 plate needed per sample
• Easy-to-read chromogenic reaction: blue colonies are Listeria spp., very easy to read on the whitish plate
• Highly specific: tested on 50 strains of Listeria spp. and 30 strains of non-Listeria species
• Certified NF VALIDATION according to the ISO 16140 standard

Principle

β-D-glucosidase activity, common to the Listeria genus, is detected using a chromogenic substrate (X-glucoside). Its hydrolysis induces the formation of a blue to blue-green color in all Listeria colonies.

PI-PLC is an enzyme only detected in pathogenic Listeria species: L. monocytogenes and L. ivanovii. AL medium contains phosphatidylinositol which, when it breaks down, produces an opaque halo around the colonies of these two bacterial species. The halo is visible after 24 hr for L. monocytogenes and 48 hr for L. ivanovii.

AL (Agar Listeria according to Ottaviani and Agosti) Chromogenic Assay

Enzymatic Activity	L. monocytogenes	Listeria spp.	Non-Listeria
Pl-PLC dectection	+	–	–
β-D-Glucosidase	+	+	–