In the antibiotic screening studies directed by Prof. Sumiki, an antifungal substance was found in a culture filtrate of a fungus, No. K-5201, which was isolated from a soil collected at Karuizawa, Nagano Prefecture. The cultural characteristics of the strain No. K-5201 were investigated by Abe and others¹⁾. The strain was designated as Paecilomyces varioti Bainier var. antibioticus, and the antibiotic produced by this strain was named variotin.

Variotin is a new antifungal antibiotic, having low toxicity and exhibiting inhibition against Trichophyton and other pathogenic fungi. This paper describes processes of production, extraction and purification of variotin and its properties.