Tolerance of certain fungi to actidione and its use in isolation of Gymnoascaceae

Vegetative cells of certain Gymnoascaceae were grown in submerged liquid culture with conc. of 1–6 mg./ml. actidione. All species grew well at these levels of actidione with the exception of one strain of Gymnoascus reessii. Pseudoarachniotus hyalinosporus grew well in the presence of 8–15 mg./ml. actidione. Ascospores, arthrospores and/or aleuriospores of certain species of Gymnoascaceae were tested for resistance to conc. of 1–6 mg./ml. actidione and they germinated and grew normally. Spores of certain Gymnoascaceae, aspergilli, penicillia and Coccidioides immitis were used to prepare a mixed spore suspension which was exposed to levels of 1–6 mg./ml. actidione. Penicillium humuli was not inhibited by actidione and overgrew the test plates. Omission of P. humuli permitted the species of Gymnoascaceae to be isolated from the mixed spore suspension.