Substrate decomposition and product release by ericoid and ectomycorrhizal fungi grown on protein

Abstract

The ericoid and an ectomycorrhizal fungus were each grown in liquid medium with protein as the sole source of nitrogen and, with the exception of one set of cultures of the ericoid endophyte, in the presence of exogeneous glucose. Dry weight yields were measured at sequential harvests and the products of protein breakdown determined. Growth of both fungi in the presence of glucose led rapidly to the release of amino-acids into the culture medium. No ammonium was detected in these cultures before the termination of growth. Results of qualitative and quantitative analyses of amino acid release are presented. When H. ericae was grown in the absence of exogenous glucose ammonium was released and growth ceased before protein utilisation was complete. The physiological and ecological complications of these observations are briefly discussed.