Antibiotic Assay Medium No.2, 2.5 kg

This medium is commonly used as base agar for microbiological agar diffusion assays for wide variety of antibiotics. Agar diffusion assays can be performed by cylinders, punched-hole or paper disc tests. This medium is identical numerically with the name assigned by Grove and Randall (1) This medium is equivalent to Antibiotic Assay Medium No.B as per Indian Pharmacopoeia (3).Peptic digest of animal tissue, yeast and beef extract provide the nitrogenous, vitamins and mineral requirement for the growth of test organisms. This medium provides solidified substratum for growth of organims and supports the overlayering of soft agar. To perform the antibiotic assay the Antibiotic assay medium No.2 is used as Base Agar. This medium should be prepared on the same day as the test. For the cylinder method, a base layer of 21 ml is required. Once the base medium has solidified, Antibiotic assay medium No.1 as seed agar, inoculated with the standardized culture can be overlaid. Even distribution of the layer is important. Storage and Shelf-life: Store below 30°C in tightly closed container and use freshly prepared medium. Use before expiry date on the label. References: 1. Grove and Randall, 1955, Assay Methods of Antibiotics Medical Encyclopedia, Inc. New York.1. 2. Indian Pharmacopoeia 2007, Minstry of Health and Family Welfare, Govt. of India, Delhi