ACQUISITION OF STREPTOMYCIN-RESISTANT( STR )MUTANTS SCREENS HIGH-YIELD MEILINGMYCIN STRAIN IN STREPTOMYCES NANCHANGENSIS / 微生物学通报

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 1521?g/mL 77. 9% higher than CK's 855?g/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.

A STUDY ON THE STREPTOMYCIN-RESISTANT (STR) MUTATIONAL SCREENING OF HIGH-YIELD NANCHANGMYCIN STRAIN / 微生物学通报

After testing the resistance of streptomycin to NS-41-80 Streptomyces Nanchangensis NS-41-80, the spores treated with 4 different dosage of super-mutagent EMS were regenerated on the lethal media, thus 3,000 streptomycin-resistant ( str ) str mutants were obtained. Then 202 spore mutants were screened through the pre-screening experiments and their yields are beyond 20% higher than the original strains respectively. In the re-screening experiments 48, 7 and 1 mutants were obtained whose yields are 100%, 200% and 300% higher than the original strains respectively and take the precentage of 23.76% and 1.60%, 3.46% and 0.23% and 0.5% and 0.03% of the number of the pre-screened strains and the rescreened strains respectively. Then 5 mutants were fermented whose yields are above 240% higher and the original strain through the continuous 3 batches fermentation, the yields are 57%～96.4% more than the original strains. Among them the yield of 80-5.3-165 is upwards of 6,000?g/mL and its norm is 5,855?g/mL. And a model of the streptomycin-resistance mutational screening of the strain producing Nanchangmycin was established.