Antimicrobial properties of chitosan-based microparticles against bacterial and fungal phytopathogens

MESAS, F.A.; TORRES NICOLINI, A.; TERRILE, M.C.; ÁLVAREZ, VERA A; CASALONGUÉ, C.A.; MENDIETA, J.R.

Campinas

Otro; São Paulo School of Advanced Science on Nanotechnology, Agriculture & Environment (SPSAS NanoAgri&Enviro); 2023

Brazilian Center for Research in Energy and Materials (CNPEM)

Traditional approaches to control phytopathogens have been based on toxic chemical compounds. The development of more sustainable and eco-friendly options is a great challenge in the present. In this sense, chitosan (CS)-based materials have emerged as a promising alternative for sustainable agriculture [1]. This study describes the synthesis and characterization, and includes a comparative biological analysis of antibacterial and antifungal activities from a set of CS microparticles (CS-MP). These particles were produced by ionic gelation using tripolyphosphate (TPP) as a crosslinker and during the synthesis process, different parameters were assayed (CS: TPP ratio, type, and time of agitation). CS-MPs were characterized by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FE-SEM). The obtained particles, designed as CS-MP1, CS-MP2, and CS-MP3 (0.19, 0.45, and 1.22 μm, respectively) exhibited contrasting zeta potential values (+7.57, +22, and +12.9 mV, respectively). We assayed the antimicrobial effect of these materials against two different phytopathogens, the bacterium model Pseudomonas syringae pv. tomato DC3000 (P. syringae) and the necrotrophic fungus Fusarium solani f. sp. eumartii (F. eumartii). Interestingly, a high value of zeta potential (CS-MP2) correlated with potent antimicrobial activity against these two types of phytopathogens, evidenced by lower IC50 and minimum inhibitory concentration (MIC) values. We discuss our findings in light of the material properties and opportunities to use CS-MPs as a new type of biomaterials in modern agriculture.