Streptomyces aureus mutant strain with high aureomycin yield and low impurity proportion and application thereof

The invention discloses a streptomyces aureus mutant strain, a breeding method thereof and an optimized culture medium. The mutant strain can efficiently synthesize and accumulate aureomycin, the content of impurity tetracycline and demeclocycline is remarkably reduced, the genetic stability is good, the form, color, aureomycin production level and main impurity content of the mutant strain are basically stable after five generations of continuous passage, and the mutant strain can be applied to industrial fermentation production and can be used as a production strain for further research and development. The optimized culture medium is beneficial to promoting synthesis and accumulation of the aureomycin, and the proportion of the impurity tetracycline and demeclocycline is further reduced. A high-yield strain breeding model is constructed based on multiple compound mutagenesis and precursor/product tolerance, the diversity of a mutation library is higher, simpleness, convenience and quickness are achieved, t