LYSINE ASSAY MEDIUM

Lysine Assay medium is formulated as described in Kavanagh. It contains all the essential growth factors for Pediococcus acidilactici ATCC 8042 except lysine. Exact concentration of lysine in the test material can be calculated by comparing results with standard curve of lysine.
Assay/Procedure: Stock cultures of the test organism Pediococcus acidilactici ATCC 8042, are prepared by stab inoculation into Lacctobacilli Agar AOAC. Incubate the cultures at 35-37?C for 16-24 hours. After incubation, centrifuge aseptically and decant the supernatant. The pellet is washed 3-4 times with 10 ml of 0.85% NaCl solution. Then resuspend the cells in 10 ml of 0.85% NaCl solution. Inoculate each tube aseptically with 1 drop of the inoculum.
It is essential that a standard curve be set up for each assay since conditions of autoclaving, temperature of incubation, etc. which influence the standard curve readings, cannot be duplicated exactly from time to time. Increasing amounts of the standard or the unknown and make up the volume to 10ml per tube containing 5 ml of the rehydrated medium. The growth response is measured turbidometrically.

for determining lysine concentration by microbiological assay method