[Standardized nutrient medium for determining the biological activity of antibiotics of the aminoglycoside group]

The possibility of the use of nutrient media containing only salt components in addition to agar-agar in determination of the biological activity of aminoglycoside antibiotics was confirmed. The optimal results were obtained on the medium including ammonium acetate, disubstituted sodium phosphate and agar-agar. Glucose was added to the medium simultaneously with the test microbe. The medium is simple by its composition. It provides satisfactory growth of B. subtilis ATCC 6633 as the test microbe and clear inhibition growth zones of sufficient size. The results of the assay of the biological activity of neomycin, monomycin, streptomycin and kanamycin on the medium of this composition were reproducible.