The occurrence of several weeds in crops of high economic value directly affects grain yield. This scenario led to the mass investigation of chemical products that circumvent these adversities and provide control potential. Nonetheless, the excessive application of chemical herbicides has generated significant concerns about the environment. Accordingly, the adoption of alternative practices, such as the application of microbial metabolites, emerges as strategic control actions, having a sustainability bias and allowing the reduction of risks of human and animal contamination. Appropriately, this study proposed to conduct a microbial prospection of microorganisms capable of producing secondary metabolites to inhibit growth and generate phytotoxicity in weeds. Furthermore, to increase the herbicidal activity, different strategies were evaluated involving microbial co-cultivation and ultrasound-assisted extraction after fermentation. Accordingly, 63 microorganisms were isolated from weeds with disease symptoms and submitted separately to submerged fermentation. Initially, the bioherbicidal activity was evaluated in Cucumis sativus plants, and the most promising were applied in Amaranthus hybridus and Echinochloa crusgalli. Treatments with fermented broth obtained from co-cultivation and ultrasound-assisted extraction after the fermentation process indicated an inhibition of plant development. The most promising strains were A14.2 and B22.2 (Nigrospora sphaerica), B14 (Bacillus velezensis), and γ (Aspergillus flavus).

This study aimed to compare the herbicidal activity of solid formulas obtained by spray drying with conventional liquid formulas containing biomolecules produced by submerged cultivation of the fungus Diaporthe sp. in a stirred-tank bioreactor. The solid formula presented the highest phytotoxicity on plant control (96.7%) and the phytotoxicity was directly related to the concentration of fermented broth in the formula. The use of adjuvant improved the efficiency of the bioherbicide. Dry matters of treatments were lower than the control and this was correlated with an increase in oxidative stress, since the activity of the antioxidant enzymes such as superoxide dismutase and guaiacol peroxidase increased in the treatment with a high level of phytotoxicity. Spray drying technology is a promising tool to concentrate bioherbicide without the loss of bioactive compounds since one of the major challenges in the production of bioherbicides is the low concentration of active ingredients in the fermented broth.

This study focused on obtaining a spray-dried powder containing chitinase and β-1,3-glucanase as active ingredients for the control of agricultural pests. Different carriers were tested in the spray drying of these enzymes. The effectiveness of the application of the enzymes was evaluated against Ceratitis capitata (Diptera: Tephritidae). The combination of maltodextrin (2.5% w/v), gum Arabic (2.5% w/v), and soluble starch (5.0% w/v) as carriers showed the best result of residual activity of β-1,3-glucanase (88.36%) and chitinase (69.82%), with a powder recovery of 45.49%. The optimum conditions for the operational parameters of the spray drying process were: inlet air temperature of 120 °C, drying airflow rate of 1.1 m³/min, feed flow rate of 5.8 mL/min, and nozzle air pressure of 0.4 MPa. The powder produced showed 65.6% efficiency for the control of the fly. These results demonstrated the possibility of using the spray drying process to obtain an enzymatic potential product for biological pest control.