Isolation of cytoplasmic membranes of Fusarium culmorum protoplasts

Abstract

Fusarium culmorum protoplasts were obtained by cell wall digestion with microbial lytic enzymes. The nature of the membrane structure of these protoplasts was studied by means of ultrathin sectioning and phase contrast and electron microscopy. When the protoplast suspensions were diluted in a protecting solution the spherical structures swelled and the membranes were disrupted with the liberation of the cytoplasmic contents. A direct demonstration of the presence of a membrane has been made by phase contrast and electron microscopy of heated membrane suspensions. The membrane seems to consist of a single or double layer, the inner portion of which appears to be fibrous. A comparison of this structure with that observed in intact cell wall preparations showed marked structural and morphological differences. Preliminary studies suggest a lipoprotein nature of the cytoplasmic membrane. The membrane preparation was of a delicate nature, structures often dissolving during the procedure of preparation.