Produção de conídios por Trichoderma asperellum via fermentação líquida submersa

Abstract

Trichoderma spp.- based products are widely used in agriculture, either for promoting plant growth and/or disease management. Large-scale production of a biocontrol agent is a challenge for the biological industry. In this sense, liquid fermentation is an interesting strategy. Thus, the objective of this work was to investigate the ideal culture medium for the production of Trichoderma asperellum (CNPMF1007) conidia, enabling its production in submerged culture. The experiment was conducted in the Embrapa Cassava and Fruits Phytopathology laboratory, and arranged in a completely randomized design, in a factorial scheme (4 x 2 x 2) with three repetitions. The treatments consisted of culture media (Martin Medium [MM], Nutrient Medium [MN], and media composed of 30% [AA30] and 50% [AA50] residues); agitation levels (constant [CO] and periodic [PE]); photoperiods (0 hours of darkness [ES] and 12 hours of light [LZ]). The assays were carried out in Erlenmeyer flasks containing 200 mL of liquid culture medium and 10 mL of the inoculum suspension (1 x 108 conidia mL-1) kept at room temperature. The evaluations were performed three days after Trichoderma inoculation in the established medium, and then the number of conidia (NC) was evaluated under a microscope, and the viability of the propagules was evaluated through colony-forming units, CFU mL-1. Culture media, agitation level, and photoperiod significantly influenced the production of NC and CFU of Trichoderma asperellum (CNPMF1007), with PE agitation and LZ photoperiod stimulating higher production of NC and CFU. This behavior was also pertinent for the AA50 culture medium (6.2x106 conidia mL-1) and (4.5 x 106 CFU mL-1) highlighted in comparison to the others, with no fluctuation between the amounts of conidia produced and viable ones.