Effect of L(-)Sorbose on the Release of {beta}-Glucosidase by Trichoderma reesei QM9414

Biochemical Engineering Research Centre, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India ABSTRACT Summary: L (–)Sorbose, a sugar known to cause paramorphogenesis in fungi, was tested for its effect on morphology and release of cell-wall bound β-glucosidase (EC 3.2.1.21 ) in the cellulolytic fungus Trichoderma reesei QM9414. Sorbose caused an increase in branching and septation in the growing mycelium. Extracellular β-glucosidase activity was enhanced when cellobiose or cellulose growth medium was supplemented with sorbose. In sorbose-supplemented cultures, the β-glucosidase activity associated with the wall fraction was less than half that in unsupplemented cultures. The intracellular activity was also lower in the sorbose-supplemented cultures than in unsupplemented controls. The glucosamine/glucose ratio of wall hydrolysates from sorbose-supplemented cultures was about twice that of control hydrolysates. Since β-glucosidase is closely associated with 1,3-β-glucan in the walls of T. reesei , a decrease in wall glucan content, and the resulting weakened association of the enzyme with the walls, is probably responsible for its increased release into the culture medium in the presence of sorbose.