Pilot production of Clonostachys rosea conidia in a solid‐state fermentor optimized using response surface methodology

The nonpathogenic, saprophytic fungus Clonostachys rosea is one of the most powerful fungal biological control agents (BCAs). However, the production of fungal BCAs is still a major constraint for their large‐scale use and commercialization. Here, we developed a novel solid‐fermentation reactor that is light transparent and ventilated both at the top and the bottom, and optimized C. rosea cultivation conditions in solid‐state fermentation using response surface methodology. The growth area of spores provided by the novel fermentor was two times that of the traditional one. A quadratic polynomial model was developed, which indicated the effects of variables on the conidia yield. The greatest spore production of 3.50 × 1010 spores/g‐dry‐matter was obtained after 11 days at the initial moisture content of 69.2% w/w, the medium thickness of 3.84 cm, and the porosity of 0.37%. The optimized spore yield was increased by one order of magnitude. The fermentation time was shortened from 15 to 11 days. With the novel solid‐fermentation reactor, increase in C. rosea spores production and decrease in fermentation time were achieved. Current data imply that both the novel solid‐fermentation reactor designed and the optimized fermentation conditions are suitable for industrial‐scale C. rosea spore production.