Optimised fermentation conditions and improved collection efficiency using dual cyclone equipment to enhance fungal conidia production

摘要

Methods for enhancing conidial yield and for harvesting pure fungal conidia of entomopathogenic fungi were investigated. Fermentation conditions (liquid-to-solid ratio, MgSO4 center dot 7H(2)O, incubation temperature, inoculum sizes, KNO3 and relative humidity) of Beauveria bassiana s.l. and Metarhizium anisopliae s.l. were optimised to increase the conidial yields that reached 11.2 mg/g and 24.5 mg/g, increases of 72% and 52% compared to the unoptimised yields of 6.5 mg/g and 16.1 mg/g, respectively. Three methods were compared for harvesting pure conidia of B. bassiana: dual cyclone equipment (DCE), sieving 200 and elution with 0.02% Tween-80 suspension. DCE performed the best, giving a conidial yield of 12.6 mg/g and 1.8 x 10(10) conidia.g (1). To further enhance the harvest efficiency, response surface methodology combined with a Box-Behnken design was employed, and the conidial yield of B. bassiana reached 20.9 mg/g, a total increase of 221% compared to the original conditions. Under these optimised harvest parameters, the conidial yield of M. anisopliae rose to 42.2 mg/g, an increase of 162%. The conidia of B. bassiana and M. anisopliae harvested in this way were pure, with no mycelial fragments or substrate visible in microscopic images.