ACQUISITION OF STREPTOMYCIN-RESISTANT( STR )MUTANTS SCREENS HIGH-YIELD MEILINGMYCIN STRAIN IN STREPTOMYCES NANCHANGENSIS

After testing the resistance of Streptomycin to the strain NS-41-80 which is the Meilingmycin producer- Streptomyces nanchangensis , a lot of streptomycin-resistant ( str ) mutants were screened after the spores regenerated on the lethal media when they were treated with 4 different dosage of super-mutagent EMS. We have abtained the high-yield strain 80-5. 11-221 from these str mutants which only produces Meilingmycin and no Nanchangmycin in the rotation-flask experiments. The productivity of 80-5. 11-221 is 1521μg/mL 77. 9% higher than CK's 855μg/mL. After the shake flask fermentation experiment of 80-5. 11-221 for six generations, the productivity of F 2 and F 3 is stable and the productivity of F 4?F 5?F 6 decreases hastily with the increment of generations. It was showed that the chemical-resistance mutation of the strains had closely relation with yield mutation and the EMS dosage of the yield mutation was higher than the resistance-chemical mutation's through the statistical analysis between the dosage of mutation and the chemical-resistance mutational frequency?the variate capacity of the mutants' yield. A model of the resistance-chemical mutational labelling rational selection of the strain producing Meilingmycin was established.