Alteration of cell wall composition leads to amphotericin B resistance in Aspergillus flavus

An amphotericin B (AmB)-resistant mutant was isolated from a wild-type AmB- susceptible strain of Aspergillus flavus by serial transfer of conidia on a gar plates containing stepwise increased concentrations of AmB up to 100 mu g ml(-1). The acquired resistance of mycelia was specific for polyene-anti biotics AmB, nystatin and trichomycin, Spheroplasts derived from the resist ant mycelia were as susceptible to AmB as the wild-type. Chemical analysis of the cell wall revealed that levels of alkali-soluble and -insoluble gluc ans were significantly higher in the resistant mycelia as compared to those in the wild-type. When resistant mycelia were treated with SDS, they adsor bed as much AmB as wild-type mycelia, These results suggest that alteration s in the cell wall components of mycelia, especially 1,3-alpha-glucan and p rotein complex in the outermost wall layer, lead to AmB resistance in A. fl avus.