This result revealed that the inhibition activity was due to the chitinolytic potential. The true fungi those belonging to the group Asco, Phyco, Basidio and Duteromycetes contain chitin as the major cell wall component. However, the phytopathogen Phytophthora infestans belongs to the group Oomycota which does not have chitin in its cell wall.
So they are resistant to the chitinase action. The other test phytopathogens showed sensitivity to different percentage towards the crude culture filtrate. During the primary screening process the partial inhibition of Phytophthora infestans may be due to the production of some other antifungal metabolites that are not produced during the fermentation in the chitinase minimal medium. Furthermore, the complete inhibition of other test phytopathogens in the primary screening process may be due to other antifungal metabolite in addition to the chitinases.