DEVELOPMENT OF BIODEGRADABLE MICROPARTICLES FOR APPLICATION IN AGRICULTURE AS BIOPESTICIDES
Microbiological control has been applied as an alternative to synthetic chemical pesticides to control pests that affect plantations and degrade food. Sensitivity to environmental variations and high volatilization of biopesticides drastically reduce the useful lives and efficiency in the field. The microencapsulation method with natural materials enables the formation of a physical barrier that protects and ensures viability, optimization of properties and increased shelf life of these products. Thus, the objective is to evaluate the encapsulation effect of Bacillus amyloliquefaciens and essential oils to control Botrytis cinerea, Colletrotrichum glocosporioides and Corynespora cassicola. The effect of nine essential oils on pathogens was evaluated. After selecting better oil, the formation process of sodium alginate/chitosan micro loaders was developed with essential oil and bacteria by the emulsion and method ionic gelation through Design of experiment. The strain of B. amyloliquefaciens showed fungicide activity of up to 73%. At the same time, the essential oils of cinnamon, clove and thyme obtained the best antimicrobial activity among the nine oils evaluated, with fungicide activity with concentrations lower than 2 μL/mL and bactericidal activity with concentrations higher than 250 μL/mL. Spherical micro loaders with continuous walls of diameters of less than 150 μm were obtained for both formulations, with polymer concentration, surfactant and stirring speed as significant factors for optimization of both encapsulation processes. Encapsulation efficiency of up to 93% and 94% were achieved for clove leaf essential oil micro loaders and B. amyloliquefaciens micro loaders, respectively. The essential oil microcarriers showed fungicide activity for the three fungi and bactericidal inhibition of 55% in 1h, but after 24 h, the strain B. amyloliquefaciens recovered cell growth for samples containing chitosan. While microloaders B. amyloliquefaciens, presented fungicide inhibition of 40, 38 and 56% for B. cinerea, C. glocosporioides and C. cassicola, respctivament.