KINETIC MODELING OF MYCOPARASITISM BY Trichoderma harzianum AGAINST Cladosporium cladosporioides ISOLATED FROM COCOA FRUITS (Theobroma cacao)

Abstract

Cladosporium strains isolated from Theobroma cacao pods identified as C. cladosporioides were confronted against Trichoderma harzianum VSL291 strain by confrontation experiments. Biocontrol index (IBC) of T. harzianum VSL 291 on C. cladosporioides observed at seven days was 76.29%. The highest proteolytic activities detected in the antagonistic strain with C. cladosporioides, Colletotrichum gloeosporioides and Corynespora cassicola cell walls were associated with increased enzymatic activities of ?-1,3 glucanases, chitinases, lipases and proteases. These results suggest that proteolytic enzymes according to their degree of induction could participate in the antagonistic effect of T. harzianum VSL291 against the fungi tested. Moreover, the highest IBC values obtained suggest that the Trichoderma strains could be capable of antagonizing more efficiently against fungal pathogens of these crops. Finally, a kinetic model based on unstructured mycoparasitism mechanism was developed; this model was designed under a system of coupled differential equations with time. This model can predict the concentrations of the enzyme activities of Trichoderma (?-1, 3 glucanases, chitinases, lipases, proteases, xylanases) in the cell walls of C. cladosporioides. Kinetic parameters were fitted to the experimental data and validated by a correlation coefficient.