For microbiological assay of antibiotics. ANTIBIOTIC ASSAY MEDIUM NO. 3 (ASSAY BROTH) (VEG.) is used for microbiological assay of antibiotics. This medium recommended by USP and FDA for the Turbidimetric antibiotic assay of Amikacin, Bacitracin, Kanamycin, Streptomycin and other antibiotics. Turbidimetric antibiotic assay is based on the change or inhibition of growth of a test microorganism in a liquid medium containing a uniform concentration of an antibiotic. After incubation of the test organism in the working dilutions of the antibiotics, the amount of growth is determined by measuring the light transmittance using spectrophotometer. The concentration of antibiotic is determined by comparing amounts of growth obtained with that given by the reference standard solutions. Use of this method is appropriate only when test samples are clear. Veg. assay broth composed of Veg. peptone, Veg. extract (nitrogen, amino acid), Yeast extract (source of Vitamin B complex), Sodium chloride (osmotic equilibrium), Phosphates (buffer) and Dextrose (carbon and energy source).