Evaluation of the biocontrol effect of Trichoderma sp. Trs GT2 extracts produced by fermentation processes against Botrytis cinerea Btcr GM3

In the present work, the evaluation of the use of Trichoderma spp. for controlling different phytopathogens of agricultural importance (Fusarium oxysporum, Rhizoctonia solani, Sclerotinia sclerotiorum, Botrytis cinerea, Colletotrichum gloeosporioides, and Phytophthora sp.) was carried out. Confrontation assays by dual culture, volatile metabolites (overlapping plate assay), and diffusible metabolites (poison medium assay) were performed to identify and select the Trichoderma strain with a greater spectrum of inhibition and the most sensitive phytopathogen. The production of hydrolytic enzymes associated with biological control by the Trichoderma sp. Trs GT2 strain (chitinase, cellulase, amylase, and lipase) was evaluated. Subsequently, the use of solid-state and submerged fermentation to produce extracts with antagonistic activity against B. cinerea was evaluated, and the production of specific activity beta 1-3 glucanase was compared. It was found that Trichoderma sp. Trs GT2 presented the greatest spectrum of inhibition against the phytopathogens evaluated, resulting in the strain of B. cinerea being the most sensitive microorganism to its effects (percentages of inhibition: dual culture 100%, volatile metabolites 100% and diffusible metabolites 28.24%). The Trichoderma sp. Trs GT2 strain showed amylase, cellulase, and chitinase activity. It also produced activity titers beta 1-3 glucanase of 13.22 U/g by solid-state fermentation (SSF) and 8.19 U/mL by submerged fermentation, as well as specific activities of (1.38 U/mg) and (14.23 U/mg), respectively. The extracts produced by both fermentation systems did not present an antagonistic effect against B. cinerea; this can be attributed to the need for interaction with the phytopathogen in question for the induction of metabolites with antagonistic activity, as well as to the confusion that the evaluation of the antagonistic effect of diffusible metabolites, through the cellophane paper technique, can generate in which the mechanism of nutrient competition can cause the inhibitory effect. This work shows that the ability of one microorganism to exert biocontrol against another can vary depending on the mechanism through which it performs and demonstrates that the antagonist-phytopathogenic interaction can promote the production of metabolites with antagonistic activity.