Interaction of the nematophagous fungus<i>Duddingtonia flagrans</i>on<i>Amblyomma cajannense</i>engorged females and enzymatic characterisation of its chitinase

Abstract

Abstract The present work aimed to evaluate the production and the characterisation of a chitinase from nematophagous fungus Duddingtonia flagrans (AC001) and observe the interaction of this fungus on engorged females of Amblyomma cajennense under laboratory conditions. In assay A, the engorged females of A. cajennense were separated and immersed for 5 seconds in a fungal suspension of 106 conidia/ml of the fungus D. flagrans and placed in Petri dishes, in the dark. In assay B, wheat bran supplemented with 1% chitin and liquid minimal medium was used [K2HPO4 (5.0 g/l), MgSO4 (0.10 g/l), ZnSO4 (0.0050 g/l), FeSO4 (0.001 g/l) e CuSO4 (0.50 mg/l)], as a substrate for chitinase production. To demonstrate the presence of chitinase in the crude extract obtained after the enzymatic extraction, a purification process was developed using a specific adsorption technique. The results from assay A demonstrated the interaction of the D. flagrans conidia produced from chitin-agar on engorged females of A. cajennense. In the assay B, D. flagrans produced a chitinase successfully, with a high value for enzyme activity. The molecular mass of semi-purified enzyme was estimated at approximately 34 kDa. It was concluded that the fungus produced a chitinase and has some entomopathogenic activity, as demonstrated here for the first time; however, it is strongly suggested that further studies are needed to elucidate the molecular mechanism of infection of target organisms by this fungus.