Folic Acid Culture Agar, 500 g

An important part of any assay is the maintenance and inoculum preparation of the test organism. Folic Acid Culture Agar is used to maintain stock cultures of a wide variety of test cultures like Lactobacillus leichmannii ATCC 7830, Enterococcus hirae ATCC 8043, Lactobacillus plantarum (casei) ATCC 8014 and Lactobacillus rhamnosus ATCC 7469 used in microbiological assay of vitamins. Folic Acid Culture Agar is formulated as described by Kavanagh (3) and recommended by AOAC (4) for maintenance of Enterococcus hirae ATCC 8043, the test organism for Folic Acid Assay Medium (3). Yeast extract and peptonized milk supply mainly the nitrogenous nutrients, vitamins and minerals essential for the growth of the test organisms. Dextrose is the energy source in the medium while tomato juice provides the growth factors. Polysorbate 80 maintains the surface tension of the medium to the optimal level while phosphate serves as buffering to the medium. Inoculate 10 mL of Folic Acid Inoculum Medium (M541) with an 18-24 hours old culture from Folic Acid Culture Agar. Incubate at 35-37 degC for 18-24 hours. Centrifuge the growth and resuspend the sediment in 10 mL of 0.85 % sterile saline, after decanting the supernatant. Repeat washing with saline, two more times. Dilute 1 mL of the washed cell suspension with 99 mL of 0.85% sterile saline (1:100). Adjust the inoculum concentration as per requirement or standard reference (4). Extreme care should be taken to avoid contamination of media or glassware used for the assay. Detergent free clean glassware should be used. Even small amount of contamination by foreign material can lead to erroneous results. Application: For the Maintenance of Atcc 8043, which is used as a Test Organism in Folic Acid Assay