The biosynthesis of metallic nanoparticles (NPs) using biological systems such as fungi has evolved to become an important area of nanobiotechnology. Herein, we report for the first time the extracellular synthesis of highly stable silver NPs (AgNPs) using the nematophagous fungus Duddingtonia flagrans (AC001). The fungal cell-free filtrate was analyzed by the Bradford method and 3,5-dinitrosalicylic acid assay and used to synthesize the AgNPs in the presence of a 1 mM AgNO 3 solution. They have been characterized by UV–Vis spectroscopy, X-ray diffraction, transmission electron microscopy, dynamic light scattering, Zeta potential measurements, Fourier-transform infrared, and Raman spectroscopes. UV–Vis spectroscopy confirmed bioreduction, while X-ray diffractometry established the crystalline nature of the AgNPs. Dynamic light scattering and transmission electron microscopy images showed approximately 11, 38 nm monodisperse and quasispherical AgNPs. Zeta potential analysis was able to show a considerable stability of AgNPs. The N–H stretches in Fourier-transform infrared spectroscopy indicate the presence of protein molecules. The Raman bands suggest that chitinase was involved in the growth and stabilization of AgNPs, through the coating of the particles. Our results show that the NPs we synthesized have good stability, high yield, and monodispersion.

This study compared the coadministration among the three nematode predatory fungi, Duddingtonia flagrans, Monacrosporium thaumasium, and Arthrobotrys robusta, in the biological control of cattle gastrointestinal nematodiasis in comparison with the use of the fungus D. flagrans alone. Five groups consisting of eight Girolando heifers were kept in paddocks of Brachiaria decumbens for six months. Each heifer received 1 g/10 kg of pellets containing the fungi (0.2 g of fungus/10 kg b.w.). Group 1 (G1) received pellets with D. flagrans and M. thaumasium in coadministration, G2 received D. flagrans and A. robusta, G3 received M. thaumasium, A. robusta, and D. flagrans, and G4 received the fungus D. flagrans alone. Group 5 (control) received pellets without fungi. The monthly mean of fecal egg count (FEC) of Groups 1, 2, 3, and 4 were 93.8, 85.3, 82.7, and 96.4% smaller than the mean of control group. The treatments with pellets containing D. flagrans or D. flagrans + M. thaumasium produced significantly better results than the D. flagrans + A. robusta or the combination of the three fungi. The associations which include A. robusta were less efficient in this study than D. flagrans alone or associated with M. thaumasium.

Background: Helminth parasites cause morbidity and mortality in both humans and animals. Most anthelmintic drugs used in the treatment of parasitic nematode infections act on target proteins or regulate the electrical activity of neurons and muscles. In this way, it can lead to paralysis, starvation, immune attack, and expulsion of the worm. However, current anthelmintics have some limitations that include a limited spectrum of activity across species and the threat of drug resistance, which highlights the need for new drugs for human and veterinary medicine. Purpose: Present study has been conducted to determine the anthelmintic activity of silver nanoparticles (AgNPs) synthesized from the extract of nematophagous fungus, Duddingtonia flagrans, on the infecting larvae of Ancylostoma caninum (L 3 ). Methods: The nanoparticles were characterized by visual, ultraviolet, Fourier-transform infrared spectroscopy, transmission electron microscopy (TEM) analysis, and X-ray diffraction. The in vitro study was based on experiments to inhibit the motility of infective larvae (L 3 ), and the ultrastructural analysis of the nematode was performed by images obtained by TEM. Results: The XRD studies revealed the crystalline nature of the nanoparticles, and FTIR results implied that AgNPs were successfully synthesized and capped with compounds present in the extract. The results showed that the green synthesis of AgNPs exhibited nematicidal activity, being the only ones capable of penetrating the cuticle of the larvae, causing changes in the tegmentum, and consequently, the death of the nematode. Conclusion: The extract of the fungus D. flagrans is able to synthesize AgNP and these have a nematicidal action.

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Strongyloidiasis is the most clinically important disease among the infections caused by geohelminths, seeing that this parasite can cause autoinfection. The use of nematophagous fungi like Duddingtonia flagrans, that have predation action on eggs and infecciososas forms of helminths, emerges as an alternative method for environmental control. For this reason, analyzing the viability of larvae and eggs of Strongyloides venezuelensis and the action of Duddingtonia flagrans AC001 in vermiculite, as well as the action of the nematophagous fungi in different growth stages, is important to elaborate and define the best culture conditions that favor the activity of the fungus. Two different growth conditions were applied: both eggs and AC001 fungi were added at the same time to the vermiculite (assay A) and the addition of eggs after the growth of the AC001 fungi in the vermiculite (assay B). To recover the L larvae, the Baermann-Moraes method was applied, followed by the counting of L dead and alive. At last, it was observed that the vermiculite enriched with organic material is an adequate culture medium not only for the growth of the S. venezuelensis but also for the growth of the D. flagrans fungus, being therefore, a satisfactory culture medium for tests of viability and predatory action of this fungus. It was also observed that the activity of the AC001 fungus is greater when it is growing concomitantly with the eggs, in other words, when it is in the adaptation phase.