Optimized biosynthesis of lytic enzymes by special Trichoderma citrinoviride

The use of Trichoderma filamentous fungi in the wide concept of biocontrol is still a highly relevant topic. The multifaceted nature of their impact on phytopathogenic microorganisms results from the species diversity and complexity of their antagonistic action. The presented research aimed to determine optimal cultivation conditions of two T. citrinoviride strains for the biosynthesis of major enzymes especially those involved in the biocontrol process. Culture conditions were optimized using a three-factor Box-Behnken design to maximize the yield of chitinase and lichenase. The following independent variables were included in the model: incubation temperature, initial pH, and supplementation with fungal biomass. As a result of statistical optimization, unprecedented activities of extracellular lytic enzyme were achieved. For the B1 and B3 strains, the optimal pH was 3.5 or 7.5, respectively, in the determination of chitinase biosynthesis. It was similar for the biosynthesis of β-1.3 and β-1.4 glucanases, but at higher cultivation temperature. The exception was the B3 strain, for which the optimal pH in glucanase biosynthesis was 5.5. The most stimulating culture temperature in the process of chitinase biosynthesis and β-1.3 and β-1.4 glucanases was above 25 °C. In that, the levels of enzyme biosynthesis and corresponding composition culture environment were confirmed to be strain-dependent.