Physicochemical Properties of Cell Surfaces from the Different Developmental Stages of the Entomopathogenic Hyphomycete Nomuraea rileyi

Abstract

Physicochemical properties of cell wall surfaces of conidia, conidial germ tubes, hyphal bodies and mycelia of the entomogenous hyphomycete Nomuraea rileyi were studied. Hydrophobicity was determined using a polystyrene microsphere adhesion assay. Microspheres bound to conidial germ tube and mycelial walls indicating that these surfaces are hydrophobic. Microspheres did not bind to hyphal body walls except at polar areas. Results from these experiments were confirmed using phase exclusion methods.Electrostatic charge characteristics of fungal surfaces were examined using DEAE (positively charged) and CM (negatively charged) beads. Cells from all growth phases adhered to DEAE but not CM beads indicating the presence of negatively charged sites on the surfaces. Degree of electronegativity as shown by FITC-poly-L-lysine binding is greatest on hyphal bodies and at the proximal end of germ tubes. Fluorescence was faint on conidia and mycelia. Cationized ferritin formed a thick capsule around hyphal body cells and a thinner but continuous layer on sheath material surrounding germ tubes; labeling of mycelial sheath was more random possibly due to the dispersed native of this material. Areas of germ tubes or mycelium not covered by sheath were sparsely labeled as were conidial surfaces. Neutralization of hydrophobicity or electronegativity did not affect passive binding of conidial or mycelial cells to monolayers of insect hemocytes.