Application

GranuCult^® PEMBA agar is used for the selective isolation of viable presumptive Bacillus cereus from Food products and animal feeds and the environmental samples in the area of food production and food handling.

Footnote

We offer two media types: the superior granulated GranuCult^® and the cost-efficient powdered NutriSelect^® culture media, depending on your needs. The designations basic, plus, or prime are added to indicate the quality control level, from basic quality control to standard QC plus to prime for full regulatory compliance.

General description

GranuCult^® PEMBA agar is a selective culture medium containing two indicator systems, mannitol and bromothymol blue, and egg yolk. B. cereus does not utilize mannitol and forms precipitates of hydrolyzed lecithin from the egg yolk.B. cereus grow as turquoise to peacock blue colonies, since the medium is slightly alkalized by its metabolites (bromothymol blue reaction). The yolk reaction (by lecithinase) also leads to a precipitate surrounding the colony, which appears in the color of the agar or similar to the colony. Growth and lecithinase activity are often so strong that the precipitation is already evident before a colony is visible.Bacillus cereus is identified by colony morphology, color, and egg yolk hydrolysis. Microscopic examination of the cell and spore morphology and the formation of intracellular lipid globules in vegetative cells is a rapid method of confirmation.Mannitol-positive bacteria form yellow colonies with a yellow zone in the surrounding medium.

Legal Information

NutriSelect is a registered trademark of Merck KGaA, Darmstadt, Germany

GRANUCULT is a registered trademark of Merck KGaA, Darmstadt, Germany

Principle

Low concentration of nutrients and the selective inhibitory component polymyxin help to attain selectivity. Although, some Proteus spp. and Gram-positive cocci also grow in the medium. The low peptone level and the addition of the pyruvate improve the egg yolk precipitation and sporulation. Bromothymol blue acts as a pH indicator to detect mannitol utilization. Enzymatic digest of casein provides carbon and nitrogen sources. Sodium chloride maintains the osmotic balance of the medium, while agar is the solidifying agent.