Proteolytic activity of extracellular products from Arthrobotrys musiformisand their effect in vitro against Haemonchus contortusinfective larvae

Arthrobotrys musiformisis a nematophagous fungus with potential for the biological control of Haemonchus contortuslarvae. This study aimed to identify and demonstrate the proteolytic activity of extracellular products from A musiformiscultured in a liquid medium against H contortusinfective larvae. A musiformiswas cultured on a solid medium and further grown in a liquid medium, which was then processed through ion exchange and hydrophobic interaction chromatography. The proteolytic activity of the purified fraction was assayed with either gelatin or bovine serum albumin as substrate. Optimum proteolytic activity was observed at pH 8 and a temperature of 37°C. Results obtained with specific inhibitors suggest the enzyme belongs to the serine-dependent protease family. The purified fraction concentrate from A musiformiswas tested against H contortusinfective larvae. A time-dependent effect was observed with 77 per cent immobility after 48 hours incubation, with alteration of the sheath. It is concluded that Amusiformisis a potential candidate for biological control because of its resistant structures and also because of its excretion of extracellular products such as proteases. The present study contributes to the identification of one of the in vitro mechanisms of action of Amusiformis, namely the extracellular production of proteases against H contortusinfective larvae. More investigations should be undertaken into how these products could be used to decrease the nematode population in sheep flocks under field conditions, thereby improving animal health while simultaneously diminishing the human and environmental impact of chemical-based drugs.