Inoculation and microelements: two important factors for enhanced conidiogenesis of Trichoderma asperellum in solid and liquid fermentation

The standardization of cultivation processes that allow high levels of conidia growth and formation is required to formulate Trichoderma products to combat fungal diseases in agronomically important crops. This study evaluated the effects of inoculation using different inoculum concentrations (1.0x105, 1.0x106, and 1.0x107 conidia mL-1) and inoculum volumes (10, 30, and 50 mL). Later, it evaluated the effect of adding microelements (CaCO3, KH2PO4, MgSO4*7H2O, and (NH4)2SO4) on the conidiogenesis of two strains of Trichoderma asperellum (GRB-HA01 and GRB-HA02) in solid-state and liquid fermentation processes. After 12 days of fermentation, the highest conidiogenesis values for Trichoderma asperellum GRB-HA01 (6.9x109±5.7x102 conidia g-1) and Trichoderma asperellum GRB-HA02 (1.3x109±1.4x102 conidia g-1) were achieved using an inoculum volume of 10 mL at a concentration of 1.0x07 conidia mL-1. Adding CaCO3 (1 g g-1), resulted in the highest conidia concentrations for Trichoderma asperellum GRB-HA01 (3.0x1011±2.5x102 conidia g-1) and Trichoderma asperellum GRB-HA02 (8.6x1010±1.1x101 conidia g-1), reducing fermentation times to 9 days. The conidiogenesis obtained with liquid fermentation was lower and affected Trichoderma asperellum GRB-HA01 (3.1x107±1.1x102 conidia g-1) and Trichoderma asperellum GRB-HA02 (3.1x109±2.8x102 conidia g-1). This study showed that inoculation and adding microelements were important factors in the conidiogenesis processes of Trichoderma asperellum GRB-HA01 and GRB-HA02. Additionally, it was evidenced that solid-state fermentations are more efficient than liquid fermentation processes.