LIGNOCELLULOSE MICROPARTICLES FROM SUGARCANE BAGASSE AS A SUSTAINABLE ALTERNATIVE FOR CONTROLLING PHYTOPATHOGENIC FUNGI

Given the damage caused by phytopathogenic fungi at different stages of the agricultural production chain, including postharvest fruit spoilage and contamination of agricultural substrates, the development of sustainable strategies for microbiological control is essential. This work proposes the use of lignocellulosic microparticles obtained from sugarcane bagasse as a multifunctional biotechnological alternative. The microparticles were produced by deconstructing the lignin-polysaccharide structure through steam explosion (120 °C/45 min) and subsequent mechanical refining (Fritsch Rotor-Mill), generating two distinct samples: non-steam-exploded and refined bagasse (NSRB) and steam-exploded and refined bagasse (SERB). To evaluate antifungal activity, 7-mm discs of the fungi Fusarium solani, Alternaria alternata, Geotrichum citri-aurantii, and Colletotrichum gloeosporioides were inoculated onto PDA medium supplemented with microparticles at concentrations of 2500, 5000 and 10000 mg/L. The plates were incubated at 30 °C for 9 days, with daily measurements of mycelial growth. Significant growth inhibition was observed only for C. gloeosporioides, in both treatments and concentrations. For F. solani, although there was no reduction in growth, inhibition of the reddish pigmentation characteristic of the species was observed, suggesting possible interference with the metabolic processes associated with pigment production. Additionally, the antioxidant activity of the microparticles was evaluated by the ABTS and DPPH methods. The samples presented distinct values: SERB demonstrated greater activity (47.70 mg Trolox/g in ABTS and 11.06 mg Trolox/g in DPPH), while MRB presented (28.02 mg Trolox/g in ABTS and 6.65 mg Trolox/g in DPPH). The results suggest that in addition to the physical action of the microparticles, their antioxidant activity played a modulatory biochemical role, interfering in essential physiological processes of fungi, such as cell differentiation (Colletotrichum) or pigment synthesis (Fusarium). Regarding the other fungal species, it is suggested to increase the concentration of microparticles for a more effective evaluation of performance. In this sense, lignocellulose microparticles derived from sugarcane bagasse, particularly those treated with steam explosion, exhibit promising antimicrobial and antioxidant properties. Its use can contribute to the control of postharvest fungi and the formulation of functional inputs aimed at plant health, adding value to waste from the sugar-energy industry and promoting the development of green technologies in the agricultural sector.