Vitamin B₁₂ assay medium

Vitamin B₁₂ Assay Medium is a Vitamin B₁₂ free medium containing all other vitamins and nutrients essential for the growth of Lactobacillus leichmannii ATCC 7830 as the test organism. Cyanocobalamin (Vitamin B₁₂, Cat.No. 95190 ) is added in increasing concentrations giving a growth response that can be measured turbidimetrically or acidimetrically. A standard curve is plotted with absorbance as a function of the vitamin B₁₂ concentration. The concentration of vitamin B₁₂ in the test sample is calculated based on the interpretation of the standard curve. Lactobacillus species grow poorly on non-selective culture media and require special nutrients for their growth. Vitamin assay media are prepared for use in the microbiological assay of vitamins. Three types of media used for the microbiological assay of vitamins are:

• The maintenance media used for carrying the stock culture
• The inoculum media for preparation of the inoculum
• The assay media for quantitation of the vitamin under test.

Vitamin B₁₂ Assay Medium is a Vitamin B₁₂ free medium recommended for microbiological assay of Vitamin B₁₂ from various test samples

NutriSelect^® Plus are powdered culture media offering

• Quality control with growth promotion test according to industry standards
• Quality assurance acc. to ISO 9001
• Cost-efficient powdered media

Ingredients (g/L)
Casein acid hydrolysate, 15.00
Dextrose, 40.00
Asparagine, 0.20
Sodium acetate, 20.00
Ascorbic acid, 4.00
L-Cystine, 0.40
DL-Tryptophan, 0.40
Adenine sulfate, 0.02
Guanine hydrochloride, 0.02
Uracil, 0.02
Xanthine, 0.02
Riboflavin (Vitamin B₂), 0.001
Thiamine hydrochloride, 0.001
Biotin, 0.00001
Niacin, 0.002
p-Amino benzoic acid, 0.002
Calcium pantothenate, 0.001
Pyridoxine hydrochloride, 0.004
Pyridoxal hydrochloride, 0.004
Pyridoxamine hydrochloride, 0.0008
Folic acid, 0.0002
Monopotassium phosphate, 1.00
Dipotassium phosphate, 1.00
Magnesium sulfate, 0.40
Sodium chloride, 0.02
Ferrous sulfate, 0.02
Manganese sulfate, 0.02
Polysorbate 80, 2.00

Suspend 8.5 g of Vitamin B12 Assay Medium in 100 ml of distilled water. Boil to dissolve the medium completely. Mix well to distribute the slight precipitate evenly. Dispense 5 ml of medium into tubes containing increasing concentrations of cyanocobalamin (Cat. No. 43107) standard or the unknown. The total volume of 10 ml per tube is adjusted by adding distilled water. Sterilize by autoclaving at 15 lbs. pressure (121°C) for 15 minutes. Cool 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