Optimization of protease production by the fungus Monacrosporium thaumasium and its action against Angiostrongylus vasorum larvae

A systematic review on products derived from nematophagous fungi in the biological control of parasitic helminths of animals

Nematophagous fungi have been widely evaluated in the biological control of parasitic helminths in animals, both through their direct use and the use of their derived products. Fungal bioproducts can include extracellular enzymes, silver nanoparticles (AgNPs), as well as secondary metabolites. The aim of this study was to conduct a systematic review covering the evaluation of products derived from nematophagous fungi in the biological control of parasitic helminths in animals. In total, 33 studies met the inclusion criteria and were included in this review. The majority of the studies were conducted in Brazil (72.7%, 24/33), and bioproducts derived from the fungus Duddingtonia flagrans were the most commonly evaluated (36.3%, 12/33). The studies involved the production of extracellular enzymes (48.4%, 16/33), followed by crude enzymatic extract (27.2%, 9/33), secondary metabolites (15.1%, 5/33) and biosynthesis of AgNPs (9.1%, 3/33). The most researched extracellular enzymes were serine proteases (37.5%, 6/16), with efficacies ranging from 23.9 to 85%; proteases (31.2%, 5/16), with efficacies from 41.4 to 95.4%; proteases + chitinases (18.7%, 3/16), with efficacies from 20.5 to 43.4%; and chitinases (12.5%, 2/16), with efficacies ranging from 12 to 100%. In conclusion, extracellular enzymes are the most investigated derivatives of nematophagous fungi, with proteases being promising strategies in the biological control of animal helminths. Further studies under in vivo and field conditions are needed to explore the applicability of these bioproducts as tools for biological control.

Colonization and destruction of ants of the genus Camponotus sp. (Hymenoptera: Formicidae) in vitro by the fungus Pochonia chlamydosporia in the southeast region of Brazil

The objective of this study was to evaluate, in vitro, the colonization and destruction of ants of the genus Camponotus sp. by the ovicidal fungus Pochonia chlamydosporia (VC4 isolate), in the southeast region of Brazil. The insects used in the experiment were worker ants of the genus Camponotus sp., collected periodically in the environment and immediately transported to the laboratory in test tubes. Then, VC4 growth was promoted in 2% chitin agar medium (2% WQ) to obtain a fungal solution containing conidia and/or chlamydospores. Two experimental groups were formed. Treated group consisted of Petri dishes containing 2% agar-water culture medium (2% WA) with nine live insects and 20 µL of fungal solution at the concentration of 15,000 conidia/chlamydospores. Control group consisted of Petri dishes containing 2% WA culture medium and nine live insects. The dishes in the treated and control groups were incubated in BOD at 25 ± 1 °C and 80 ± 10% relative humidity for 4 days. After 4 days, it was observed that the VC4 had grown, colonized, and caused the destruction of the ants. The fungus P. chlamydosporia was efficient at colonizing and destroying the urban ants collected on an experimental basis. Thus, it could open up new ways to reduce the use of chemical compounds in the future, decreasing health and environmental problems.

Proteolytic activity of the nematophagous fungus Arthrobotrys sinensis on Angiostrongylus vasorum larvae

Background

The predatory nematophagous fungus Arthrobotrys sinensis (SF53) produces three proteases with nematicidal activity when grown on solid media culture. However, the proteolytic profile produced by this fungus, when grown in liquid culture medium remains unknown.

Findings

Thus, the objective of this work was to evaluate the production of proteases from nematophagous fungus Arthrobotrys sinensis in liquid medium and its nematicidal activity on first stage larvae of A. vasorum. Proteases were obtained in its crude form, using Whatman no.1 filter paper, followed by centrifugation for 5 min at 10 × g and 4°C. A zymogram was performed with co-polymerized casein in an acrylamide gel as substrate. An in vitro assay to evaluate the nematicidal action of the proteases of A. sinensis (SF53) produced in liquid medium on A. vasorum L₁ was conducted. By the analysis of the zymogram, it was observed a single halo at the beginning of digestion of the gel, suggesting that the three proteases of SF53 are produced in an enzymatic complex of large molecular weight. Regarding nematicidal activity, within 24 hours, the proteases produced in liquid medium of A. sinensis (SF53) showed a percentage reduction of 64% on the number of L₁ of A. vasorum.

Conclusion

In the present work, it is suggested that the three proteases of SF53 are produced in an enzymatic complex and was also demonstrated that these enzymes were effective in destroying A. vasorum L₁.

Statistical experimental design to assess the influence of enzymes of nematophagous fungi versus helminths

The present work used Plackett-Burman experimental design to assess the influence of enzymes of nematophagous fungi versus Strongyloides westeri and trichostrongylides larvae and Platynosomum fastosum eggs. The variables studied in the Plackett-Burman design were the proteases and chitinases of AC001 or VC4 as destructive agents of S. westeri and trichostrongylides larvae, and P. fastosum eggs. All tested enzymes had a significant effect (P < 0.05) on the destruction of S. westeri larvae. Furthermore, only VC4 and AC001 proteases showed a significant effect (P < 0.05) on the destruction of trichostrongylides larvae. On the other hand, chitinases of VC4 showed the highest significance (P < 0.05) on the destruction of P. fastosum eggs. It is proposed that statistical planning for the use of enzymes derived from nematophagous fungi is a viable way to elucidate some questions about their mechanism of action.