Temperature and growth media affect conidia production, germination and virulence of Metarhizium spp. during...

Solid State Fermentation (SSF) scale-up constraints (oxygen diffusion, heat accumulation, mass transfer and irreproducibility) pose significant obstacles to the production of biopesticides, such as entomopathogenic fungi (EPF). Understanding the responses of thermotolerant fungal strains is key to overcome these constraints. However, combination of relevant parameters for fungal growth and sporulation (temperature, growing media and time) may affect insecticidal activity (conidia production, germination and virulence), but this is not fully understood. Here, two thermotolerant strains of the EPF Metarhizium (Metarhizium brunneum EAMa 09/01-Su and Metarhizium robertsii EAMa 01/158-Su) were studied by combining the three parameters of relevance for SSF. Production conditions affected both quantity (conidia production) and quality (conidia germination and virulence) of the obtained bioproduct. Both strains were suitable for thermotolerant conidia production, with the M. brunneum strain being superior in Tenebrio molitor infection and conidial germination and the M. robertsii strain exhibiting faster germination and higher conidia production. These results provide valuable knowledge and serve as starting point for future works in production scale-up via SSF.