Effect of Rapamycin on Filamentous Fungal Cell Walls

Abstract

Filamentous fungi are widely used in the bioprocess industry to produce a variety of products resulting in billion dollar returns. Often times in industrial bioprocesses, fungi experience nutrient limitation, and we hypothesize that autophagy, a nutrient starvation response, is induced. We further hypothesize that autophagy leads to changes in the mechanical properties of filamentous fungal cell walls, resulting in thinner, weaker and stiffer walls. We test this hypothesis here, using rapamycin (an immunosuppressant drug) to gratuitously induce autophagy in the model fungi Aspergillus nidulans. Atomic force microscopy (AFM) is used to assess the mechanical properties of the cell wall, electron microscopy is used to assess wall thickness and a novel fragmentation assay is used to determine relative tensile strength of the culture. We will report on these studies and how they support our hypotheses.