Determination of ichthiomycin concentration by biological test with Cyprinus carpio L.

We have found out that one-year-old carps are extremely sensitive to ichthiomycin in concentrations between 25-125 micrograms/dm3. This fact permitted the use of biological methods for determination of ichthiomycin concentrations in cultural medium of Streptomyces levoris 1107 or crude preparations of the antibiotic.

[The dissociation of a mutant strain of Streptomyces levoris 41-08, a producer of ichthiomycin]. / Prouchvaniia vurkhu disotsiatsiiata na mutanten shtam Streptomyces levoris 41-08, produtsent na ikhtiomitsin.

The population of Streptomyces levoris 41-08, producer of ichtiomicin, is established to be unhomogeneous and consisting of four types of morphologically different varieties: light grey, white, oligospore and asporogenous. The morphological varieties differ in their biochemical activity. The most promising for the ichtiomicine biosynthesis is the grey variant, some of whose representatives manifest up to 30% higher activity than the controls. The statistical processing of data shows that the oligospore and the asporogene variants with their limits of activity to 121.8 and 119.3% respectively are promising too, while the existence of white representatives in the population is not recommended since they are low-active minus variants.