Desenvolvimento de nanopartículas com potencial biofungicida

Abstract

Agriculture always needs to overcome problems such as coping with water stresses, maintaining the planted area and increasing production, avoiding pesticides and seeking ecologically correct solutions, among other challenges. In addition, there is the concern to reduce the use of non-renewable raw materials that have been overused due to climate-related losses in the soil, such as high leaching of minerals caused by rainfall, or to avoid soil and water contamination by highly toxic, synthetic pest and disease control agents called agrotoxins. This can be overcome by using new sustainable technologies that can be considered for increased productivity, production of "green fertilizer" varieties, and use of biological control. The use of nano and microencapsulation techniques of biological control agents and growth promoters with bioavailable and biodegradable materials in the environment is a good alternative to reduce the use of non-renewable materials and increase efficiency. Thus, the present work has as main objective the development of a nanoparticulate system for biological control. The anoparticulate system was produced from the ionotropic gelation technique using chitosan as polymer and sodium tripolyphosphate as cross-linking agent. The fermentation supernatant (SFM) of the microorganism Bacillus velezensis strain Labim 22 was used for nanoparticle production since it has preliminary studies that its metabolites have action in biological control. The nanoparticles produced were prepared in different pHs, chitosan concentrations, proportions of sodium tripolyphosphate and SFM and evaluated the use of surfactants to stabilize the formulation as the Tween 80, besides testing the antimicrobial activity of the encapsulated material against the fungus Sclerotinia sclerotiorum. The encapsulated samples with concentration variation from 20% to 80% of SFM and 0.25% and 0.8% of chitosan showed 100% inhibitory action against Sclerotinia sclerotiorum separately the maximum effect is only presented in the conditions above 50% of SFM, showing that there is synergistic effect between chitosan and SFM. The samples stabilized with 0.50% Tween 80 did not show aggregation and precipitation in solution after the 26th day of the study.