Alteration of Cell Wall Composition Leads to Amphotericin B Resistance in Aspergillus flavus

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Abstract
An amphotericin B (AmB)‐resistant mutant was isolated from a wild‐type AmB‐susceptible strain of Aspergillus flavus by serial transfer of conidia on agar plates containing stepwise increased concentrations of AmB up to 100 μtg ml−1. The acquired resistance of my celia was specific for polyene‐antibiotics AmB, nystatin and trichomycin. Spheroplasts derived from the resistant mycelia were as susceptible to AmB as the wild‐type. Chemical analysis of the cell wall revealed that levels of alkali‐soluble and ‐insoluble glucans were significantly higher in the resistant mycelia as compared to those in the wild‐type. When resistant mycelia were treated with SDS, they adsorbed as much AmB as wild‐type mycelia. These results suggest that alterations in the cell wall components of mycelia, especially 1,3‐α‐glucan and protein complex in the outermost wall layer, lead to AmB resistance in A. flavus.