Black-pigmented cultures of Trichophyton rubrum var. nigricans produce an antibiotic called rubronigrin. Effective extraction and purification methods are described. The substance is effective against a broad range of fungi including Cryptococcus, Candida, Aspergillus, Mucor, and others.
Frágner P., Múčka V. (1966): Rubronigrin, new antibiotic substance from Trichophyton rubrum var. nigricans. – Česká Mykologie 20(3): 182–183.