TOS-propionate agar medium

TOS-propionate agar medium is specifically prepared for selective enumeration of Bifidobacteria in dairy products. Casein hydrolysate and yeast extract provide essential sources of nitrogen and other growth nutrients like vitamin B complex. The medium contains highly purified Galacto-oligosaccharides and sodium propionate that acts as an excellent growth promoting substances for Bifidobacteria. Cysteine hydrochloride helps in creating reduced conditions required for the growth. Ammonium sulphate and magnesium sulphate are a source of divalent cation, nitrogen, and sulphate. Lithium mupirocin is an antimicrobial supplement that inhibits the growth of most lactic acid bacteria, commonly found in fermented and non-fermented dairy products

TOS-propionate agar medium is recommended for enumeration of presumptive Bifidobacteria by colony count technique from milk products.

Suspend 62.02 grams of dehydrated media in 950 ml distilled water (1 liter fornon-selective media). Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 115°C for 15 minutes.
For selective isolation of Bifidobacteria add contents of 2 x 25 ml vials of Lithium mupirocin Supplement (Cat. No. 69732). Mix carefully to avoid the formation of air bubbles and dispense as desired.
Note: This medium being sensitive to heat, excessive heat treatment may therefore indicatively influence the properties of the medium. For more selectivity Glacial acetic acid (Bifido Selective Supplement B, Cat. No. 90577) may also be added. After addition of Bifido Selective Supplement B pH of the medium will shift to the acidic side, which does not affect the performance of the medium.

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.

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

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