Observations on Streptomyces Griseus. VI. Further Studies on Strain Selection for Improved Streptomycin Production

SUMMARY

Through the use of ultraviolet light, x-rays and natural selection, mutants were obtained that were capable of producing markedly higher streptomycin broth potencies than the starting culture. The highest streptomycin activities observed were over eight times more than the broth potencies produced by the starting culture, Waksman No. 4, under the same experimental conditions. Many thousands of cultures were examined in the selection of cultures described in this paper.

The selectivity that often results from the experimental conditions used in screening cultures is emphasized.