Mutagens for regeneration of an antibiotic-producing strain of Aspergillus versicolor.

The individual colonies of a partially degenerated culture of Aspergillus versicolor vary widely in their ability to produce an antibiotic active against Trichophyton rubrum. Mutagenic treatment with nitrous acid or ultraviolet light gave potent colonies. Nitrous acid gave better results in terms of stability and yield. This treatment may therefore prove useful in the regeneration of partially degenerated cultures.