Improvement Of Streptomyces Mycarofaciens By Genome Shuffling

Streptomyces mycarofaciens produce two antibiotics-Midecamycin and Meleumycin.Their difference lie in quantity of A1 constituent. The former contains 35-75% while the latter more than 75%. Industrial problems mainly exist in low production、expensive cost and low yield of A1. We got high-productive fusion strain of Al as well as overall production through genome shuffling between two Streptomyces mycarofaciens strains with different inheritance background.Stable initial strain B15 was harvested by natural incubation first screening and re-screening of Streptomyces mycarofaciens var.109S. High-productive mutant B64-5(precursor X-1 resistant) was got after UV and NTG combinative mutation treatment of B15. Its productivity of which showed an increase of 33% and enhancement of A1 by 16%. Its productivity remained stable after 4 generation. Optimization of high-productive mutant B64-5 fermentation process showed fermentation period was 52h、optimal timing of precursor X-1 addition is Oh and optimal addition quantity is 0.3mg/ml. All above provide foundation for Streptomyces mycarofaciens genome shuffling.Parent strain 12-2(9) X-1s Amr (duplicate mdmB, Am resistant and precursor X-1 sensitive) was descended from Am resistant plate(Am:10μg/ml) and precursor X-1 resistant plate(X-1:6mg/ml) selection.Genome shuffling between B64-5(X-1rAms) and 12-2(9)(X-1sAmr) was carried out for 3 cycles and production of high-productive fusion strain GS3-38, GS3-45, GS3-57, GS3-60 show increase by 54%,55%,44%,48%,respectively.