Abstract: In this research the over-expression strains with positive-regulating gene wysR synthesized from Wuyiencin were utilized as primary materials, 35 relatively optimal strains were selected from 2060 individual colonies of over-expression strains by agar blocks, then 9 high-yield strains were screened out adopting the method of shake flask fermentation. Ultimately, the strain W-273 was determined as the optimal strain by genetic stability analysis. Comparing the physiological and morphological characteristics between the strain of W-273 and original CK-15, W-273 strain grew faster, the production of spore was higher, and the time of spore production was in advance. The time to complete spore production for W-273 strain was 3-4 d, and this was in advance for 3-4 d than the original strain CK-15. Through electron microscope observation, the spores of W-273 were oval or rod, and the CK-15 strains were circular. Shake flask fermentation showed that strain W-273 had a higher metabolism compared to strain CK-15, antibiotic production increased 79%-289%, and the best fermentation time shortened 4-8 h.

Key words: Wuyiencin, over-expression strain, wysR gene, screen