Secreted chitinase involved in the degradation of chitin, a component of the cell walls of fungi and exoskeletal elements of some animals (including worms and arthropods). Plays a morphogenetic role during apical growth, cell division and differentiation (cell wall morphogenesis). Acts also as an antifungal agent. Involved in the degradation and further assimilation of phytopathogenic fungi, namely mycoparasitism, the major mechanism accounting for the antagonistic activity against phytopathogenic fungi displayed by Trichoderma. Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide (1->4)-beta-linkages in chitin and chitodextrins. The antagonistic activity of Trichoderma harzianum is used for the control of several soil borne plant pathogenic fungi. Belongs to the glycosyl hydrolase 18 family. Chitinase class V subfamily.