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<0.05) on
chitinase production. The conditions of maximum
chitinase activity were calculated, with the following values: incubation time 2 days, and moisture 511%. The
protease and
chitinase derived from D. flagrans, individually or together (after 24h), led to a significant reduction (p<0.01) in the number of intact cyathostomin L3, 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<0.05) between the group treated with
proteases in relation to the group treated with proteases+chitinases. In this study, the assay with the cyathostomins showed that
chitinase had a nematocidal effect, suggesting that this
enzyme acts on the "fungus versus nematodes"
infection process. It is known that nematode eggs are rich in
chitin, and in this case, we could think of a greater employability for this
chitinase.