Natural resistance of the mycelial culture of the mushroom,Panaeolus papillonaceus,towards growth inhibition by polyene antibiotics

The mycelial culture of the mushroomPanaeolus papillonaceus showed high tolerance (150 g/ml) of polyene antibiotics (nystatin, amphotercinin B) present in the growth medium and protoplast of the fungus regenerated normally in the presence of the antibiotics. Both antibiotics inhibited growth of other mushroom strains at concentrations from 10 g/ml to 20 g/ml. Because polyene antibiotics interact with free membrane sterol of the sensitive fungi, the sterol present in the mycelia ofP. papillonaceus was studied. Extraction of sterol from the mushroomP. papillonaceus required primary treatment of the dried mycelia with alkali, and only ergosterol was identified as present as the extracted sterol. No sterol or sterol conjugate (fatty acid ester) could be extracted directly from the mycelia by petroleum ether, chloroform, or methanol without prior alkali treatment. Homogenization of the mycelia and subsequent treatment of the homogenate with detergent or chaotropic ions did not release any sterol conjugate in the aqueous phase. The unique nature of the sterol component present in the mycelia ofP. papillonaceus was indicated.