[Selection of ningnanmycin overproduction strains by resistance of self-secondary metabolites].

The S. noursei var. xichangensis FR-5 protoplasts was treated by UV, NTG in sequence, and the mutated strains were selected by use of self-secondary metabolites, the microorganisms were isolated by fermentation after agarblock rational method. The seven strains of microorganisms which were one fold production higher than that of original strain were obtained from 122 mutants. The method should be a simple, high speed selection model of breed Ningnanmycin overproduction strains of microorganisms.