H. Christine Reilly

A rapid method for demonstrating the identity of streptomycin-producing strains of Streptomyces griseus.

Summary A method for the rapid isolation and identification of streptomycin-producing strains of Streptomyces griseus is described. The method consists in plating; out various dilutions of material from natural substrates, using agar media to which 25 μg/ml streptomycin has been added. Colonies of actino-mycetes developing on the plates are picked and transferred to agar slants. When the cultures have developed, they are used to make agar streaks on plates. The plates are incubated for 24 hours, and drops of actinophage placed upon some of the streaks. The destruction of the growth of the actinomyces will prove the identity of the culture with streptomycin-producing S. griseus. This identification can be confirmed by the use of the agar-streak method, using various test bacteria, the sensitivity of which to streptomycin is known. Finally the cultures are grown in media used for the production of streptomycin, and the antibiotic produced is compared with streptomycin.