Regulation of protein secretion by mycelial culture of the mushroom Termitomyces clypeatus

Termitomyces clypeatus secreted a 24-kDa xylanase constitutively in xylan medium, bur required a gluconeogenic amino acid or Krebs cycle acid for the secretion of a 56-kDa amyloglucosidase in dextrin medium. Aspartate, glutamate, succinate and fumarate all increased secretion of amyloglucosidase from 50% to > 90% and enzyme production by 10-fold with little effect on xylanase production. Glutamate or succinate stimulated in vitro release of intracellular amyloglucosidase from washed mycelia in the presence of cycloheximide. Amyloglucosidase accumulated in the absence of glutamate was a high-molecular-mass protein that did not migrate in PAGE. Cellular regulation by the fungus of the secretion of amyloglucosidase is indicated.