ANTIBIOTIC ASSAY MEDIUM NO.4 (VEG.)

Antibiotic Assay Medium No. 4 (Veg.) is a vegetable peptone-based culture medium commonly used for the microbiological assay and determination of antibiotic residues in milk. It has been formulated with vegetable-derived peptones to replace animal-origin components, thus posing no risk of BSE/TSE, while ensuring performances that are comparable to the traditional Antibiotic Assay Medium No. 4. It is employed in the pharmaceutical QC labs, dairy food industry labs, and academic research labs for the assay of antibiotics and detection of antibiotic residues.

This medium has been formulated with ingredients in conformance with regulatory requirements specified, including those by the Food and Drug Administration (FDA), and is equivalent to the medium specified by Grove and Randall.

The medium permits rapid growth of the indicator organisms such as Bacillus stearothermophilus and Micrococcus luteus, as recommended for the determination of the concentration of antibiotics. For milk, the penicillin tests are generally performed on the basis of inhibition paper disk or cylinder plate methods. Antibiotic inhibition of bacterial growth is revealed by a clear and precise inhibition zone. Veg peptones, yeast extract, and vegetable extracts render nutrient factors (amino acids, vitamins, and growth factors) necessary for rapid and balanced microbial growth. Dextrose as an easily metabolized carbon and energy source enhances luxuriant microbial growth and provides sharply defined inhibition zones.

This medium is used for the detection of Penicillin-G in milk using Bacillus stearothermophilus.