Location of cellulolytic enzyme activity in the marine fungus Trichocladium achrasporum

Abstract
Cellulase activity in Trichocladium achrasporum was demonstrated by its ability to produce cell-associated and extracellular cellulolytic enzymes when grown on a crystalline cellulose substrate. In addition, azure dye was solubilized from dyed crystalline cellulose, appearing in the growth medium during the phase of cell lysis. Exoglucanase activity was highest in the culture filtrate, with slight activity in the cell fractions, while endoglucanase was associated only with the mycelium. No desorbable exoglucanase nor endoglucanase activity could be released by sonication of residual cellulose particles removed from actively growing cultures. β-Glucosidase activity was located only in the cell-associated fractions during active growth. All enzymes had optimal activity at 50 °C; in the particulate fraction β-glucosidase exhibited a second optimum at 30 °C. In the filtrate, soluble intracellular and particulate fractions optimal exoglucanase activity occurred at pH 6.4, 7.0, and 5.8, respectively. Endoglucanase activity was optimal at pH 5.8 in the soluble cell fraction, and at pH 5.4 in the particulate fraction.