Procedure for isolating the endophyte from tall fescue and screening isolates for ergot alkaloids

Abstract

A procedure was developed to isolate and determine ergot alkaloid production by Acremonium coenophialum, the endophytic fungus of tall fescue. The procedure established that macerated leaf sheath or pith from inflorescence stem placed either in a liquid medium or on a corn meal-malt extract agar medium produced isolated mycelium and characteristic conidia within a 3- to 3.5-week period. Once isolated, each fungus was placed in another liquid medium, M104T, where competent strains produced total ergot alkaloids ranging from 38 to 797 mg/liter. Several isolates were negative for ergot alkaloid synthesis. The production of ergot alkaloids by individual isolates was unstable; isolates rapidly degenerated in their ability to produce ergot alkaloids during subculture. However, the procedure as presented allows the assessment of an isolate for ergot alkaloid synthesis during its initial isolation.