SECRETION OF BETA-GLUCOSIDASE BY TERMITOMYCES-CLYPEATUS - REGULATION BY CARBON CATABOLITE PRODUCTS

Casamino acids, irrespective of carbon source used, highly stimulated extracellular production of beta-glucosidase by T. clypeatus, which produced very low amounts of enzyme in the presence of 1% (w/upsilon) sugar including xylose in minimal growth medium. Casamino acids did not affect the rate of sugar uptake or improve glucose transport by mushroom, but they significantly reduced the intra/extracellular enzyme ratio by increasing the secretion of the enzyme from the cell pool into the culture filtrate. No phosphoenol pyruvate-mediated transport of sugars was detectable in the fungi. Few amino acids utilized as carbon source by the mushroom and Krebs cycle acids (poorly supporting growth) showed activities on enzyme production similar to that of casamino acids. Nonmetabolizable glucose analogue glucosamine also increased extracellular enzyme production. Liberation of enzyme from washed mycelia was stimulated by the presence of glutamate in the incubation mixture and was also found to be insensitive to cycloheximide (30-mu-g ml-1). Regulation of the excretion of beta-glucosidase in T. clypeatus by glucose catabolic product(s) was indicated.