Nematocidal activity of extracellular enzymes produced by the nematophagous fungus Duddingtonia flagrans on cyathostomin infective larvae

Abstract Duddingtonia flagrans produces chitinases, however, optimization of the production of these enzymes still needs to be explored, and its nematocidal activity should still be the subject of studies. The objective of the present study was to optimize chitinase production, and evaluate the nematocidal activity of extracellular enzymes produced by the nematophagous fungus D. flagrans on cyathostomin infective larvae. An isolate from D. flagrans (AC001) was used in this study. For the production of enzymes (protease and chitinase), two different culture media were inoculated with AC001 conidia. Both enzymes were purified. The statistical Plackett–Burman factorial design was used to investigate some variables and their effect on the production of chitinases by D. flagrans . After that, the design central composite (CCD) was used in order to determine the optimum levels and investigate the interactions of these variables previously observed. Only two variables (moisture and incubation time), in the evaluated levels, had a significant effect ( p D. flagrans , individually or together (after 24 h), led to a significant reduction ( p 3 , when compared to the control, with following reduction percentage values: 19.4% (protease), 15.5% (chitinase), and 20.5% (protease + chitinase). Significant differences were observed ( p