Optimizing protease production from an isolate of the nematophagous fungusDuddingtonia flagransusing response surface methodology and its larvicidal activity on horse cyathostomins

Abstract

AbstractProtease production fromDuddingtonia flagrans(isolate AC001) was optimized and the larvicidal activity of the enzymatic extract was evaluated on infective horse cyathostomin larvae (L3).Duddingtonia flagranswas grown in liquid medium with eight different variables: glucose, casein, bibasic potassium phosphate (K2HPO4), magnesium sulphate (MgSO4), zinc sulphate (ZnSO4), ferrous sulphate (FeSO4), copper sulphate (CuSO4) and temperature. The Plackett–Burman analysis showed a significant influence of MgSO4, CuSO4and casein (P < 0.05) on protease production byD. flagransin liquid medium. Central composite design indicated that the highest proteolytic activity was 39.56 U/ml as a function of the concentrations of casein (18.409 g/l), MgSO4(0.10 g/l) and CuSO4(0.50 mg/l). A significant difference (P < 0.01) was found for the larval number between the treated and control groups at the end of the experiment. A reduction of 95.46% in the number of free-living larvae was found in the treated group compared with the control. The results of this study suggest that protease production byD. flagrans(AC001) in liquid medium was optimized by MgSO4, CuSO4and casein, showing that the optimized enzymatic extract exerted larvicidal activity on cyathostomins and therefore may contribute to large-scale industrial production.