Atividade antibacteriana de nanopartículas de prata de Trichoderma sobre Aeromonas spp. provenientes de piscicultura

Abstract

Nanoscience studies phenomena that occur on a nanoscale. Nanotechnology in turn is the application of nanoscience in obtaining and studying nanometric materials. Among these nanomaterials, there are silver nanoparticles that have the most diverse applications, with antimicrobial activity being the most widespread in times when antimicrobial resistance is considered a serious problem. These nanoparticles can be obtained from chemical, physical and biological synthesis, the latter being more advantageous if compared to the others because it is considered ecologically correct because it is less polluting and low cost. This study aimed to evaluate the potential of four Trichoderma strains to biosynthesize silver nanoparticles. The strains Trichoderma brevicompactum P16D2, T. harzianum P4A, T. inhamatum P21C and T. tomentosum P14C2 were evaluated. The fungus T. harzianum P4A was the most efficient, being detected the color change of the mycelial filtrate after 24 hours. The color change of the others occurred after 72 hours of biosynthesis. Partial characterization was performed, and surface plasmon resonance bands with peaks of 405 and 425 nm were detected. DLS analysis was performed only with the colloidal solution of T. harzianum P4A and T. inhamatum P21C, where the hydrodynamic size was 72.22 and 73.82 nm; zeta potential of -29.3 and -8.03 mV and polydispersity index of 0.256 and 0.357, respectively. An antibacterial test was carried out with the colloidal solution of nanoparticles of the four fungi against fifteen strains of Aeromonas spp. obtained from skin lesions and kidney of tambaqui, and strains of ATCC reference, these being Aeromonas hydrophila, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. The largest zones of inhibition were 10.19 and 14.43 mm for T. brevicompactum P16D2, 10.30 and 11.54 mm for T. harzianum P4A, 11.03 and 13.20 mm for T. inhamatum P21C, 10, 32 and 13.76 mm for T. tomentosum P14C2. The mycelial filtrate of T. harzianum P4A and T. tomentosum P14C2 showed zones of inhibition, where the highest values ranged from 14.79 to 16.07 mm and 8.80 to 9.55 mm, respectively. A significant reduction in antibacterial activity was observed after a long time of preservation of the nanoparticles, suggesting that optimizations of the biosynthesis parameters are necessary to avoid the loss of antibacterial activity and make it more efficient.