Culture medium improvement for Isaria fumosorosea submerged conidia production

[Production of infectious units of Isaria fumosorosea (Hypocreales: Cordycipitaceae) from different indigenous isolates of northeastern Mexico using 3 propagation strategies]

The aim of this study was to evaluate the production of blastospores and conidia of different native isolates and a strain of Isaria fumosorosea using different propagation techniques. Two liquid culture media of casamino acids and peptone as nitrogen sources and glucose as carbon source for both media cultures were respectively used in the production of blastospores, while for the production of conidia, the fungi were grown in potato dextrose agar; from these cultures, solutions of conidia to a concentration of 1×10⁶ per milliliter were prepared to inoculate flasks with Sabouraud dextrose broth for the liquid phase of the biphasic culture, also known as preculture. Subsequently, rice grain bags were inoculated with the preculture and the conidia solutions, which were incubated for 14 days for solid fermentation and biphasic culture, respectively. The HIB-23 isolate recorded a concentration of 4.90×10⁸ blastospores/ml in the casamino acid medium, while a concentration of 2.15×10⁸ blastospores/ml was obtained in the peptone collagen medium. For the Pfr-612 strain, the conidia production in solid-state fermentation was 1.58×10⁹ conidia/g, and for HIB-30 in the biphasic culture of 9.00×10⁶ conidia/g. Solid-state fermentation proved to be the most effective method with an average of 1.09×10⁹ conidia/g, whereas the biphasic culture was the least effective method with 2.76×10⁶ conidia/g; no significant difference was reported for the submerged production media.