Optimization of promoting conidial production of a pinewood nematode biocontrol fungus, Esteya vermicola using response surface methodology.

Hydrogen peroxide was applied for promoting sporulation of Esteya vermicola and response surface methodology was used to optimize the effect of processing parameters on sporulation. Three variables were concentration (X 1), treatment time (X 2), and carbon-to-nitrogen ratio (X 3). The results indicated that X 1 and X 2 and the quadratic term of X 1 had significant effect on the sporulation, followed by the significant interaction effects between X 1 and X 2. The optimal conditions of promoting sporulation were as follows: hydrogen peroxide concentration 1.65 mM, treatment time 9.40 min, and carbon-to-nitrogen ratio 9:1. Under these conditions, sporulation increased twelve times compared with control and this result was in agreement with model predictions.