Pantothenate Assay Medium, AOAC

Intended Use

Recommended by AOAC for microbiological assay of pantothenic acid or its salts using Lactobacillus plantarum ATCC 8014 as the test organism.

Composition**

Final pH (at 25°C): 6.7±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 7.3 grams in 100 ml distilled water. Heat to boiling to dissolve the medium completely. Mix well to distribute the slight precipitate evenly. Dispense in 5 ml amounts to each assay tube in increasing amounts of the standard or the unknown. Adjust the volume of each tube to 10 ml with distilled water. Sterilize by autoclaving at 15 lbs pressure (121°C) for 10 minutes. Cool the medium immediately. Generally satisfactory results are obtained with Pantothenic acid at levels of 0.0, 0.005, 0.01, 0.015, 0.02 and 0.025 microgram per assay tube (10ml).

Principle And Interpretation

Pantothenate Assay Medium is a dehydrated medium free from pantothenic acid or pantothenate but containing all other nutrients and vitamins essential for the cultivation of L. plantarum ATCC 8014 as recommended by AOAC (1). To obtain a standard curve pantothenate is added in particular increasing concentrations giving a growth response that can be turbidimetrically measured. A standard curve is drawn on graph paper the in the following way. Plot the absorbance as a function of the pantothenate concentration and the best curve is drawn through the points. The concentration of pantothenate is calculated by interpretation on the standard curve.

Quality Control

Appearance Off-white to light yellow homogeneous free flowing powder

Colour and Clarity of prepared medium Light yellow coloured clear solution, which may have a slight precipitate.

Reaction

Reaction of 7.3% w/v aqueous solution at 25°C. pH: 6.7±0.2

pH

6.50-6.90

Cultural Response

Microbiological Assay of Pantothenate is carried out by using L.plantarum ATCC 8014 after an incubation at 35-37°C for 18-24 hours.

Growth

Good growth is obtained. Gradual increase in growth with increasing concentration of pantothenate standard levels of 0.0, 0.005, 0.01, 0.015, 0.02, 0.025 mcg per assay tube is recorded as equivalent increase in absorbance at 620 nm.

Storage and Shelf Life

Store below 8°C and use freshly prepared medium. Use before expiry date on the label.

Reference

1. Williams, (Ed.), 2005, Official Methods of Analysis of the Association of Official Analytical Chemists, 19th Ed., AOAC, Washington, D.C.