Criteria for the selection of strains of entomopathogenic fungi Verticillium lecanii for solid state cultivation

The objective of this study was the selection of strains of Verticillium lecanii for solid-state fermentation (SSF) containing cuticle of Sphenarium purpurascens as an inducer of proteases and chitinases. The selection criteria were: growth at low water activity (aW), enzymatic activities (proteases and chitinases) and CO2 production rate. Three strains of V. lecanii were studied ATCC 26854, ATCC 46578 and a wild strain (WS). The strains ATCC 26854 and WS presented the best biomass production at low aW (0.957). Highest rates of clearing zones of casein and chitin were obtained for strains ATCC 26854 and WS. Best results of CO2 production in SSF were obtained by using V. lecanii ATCC 26854 which showed a maximal value (2.3 mg CO2 g IDM−1 h−1) at 36 h of cultivation. Although clearing zones of casein and chitin were partial criteria for strain selection. It was concluded that growth a low water activities and CO2 production rate, were more reliable criteria for selecting strains of V. lecanii for solid state culture using cuticle of insect as the main C and N source.