Avaliação de diferentes meios de cultura para a produção de conídios pelo fungo Hirsutella thompsoni

Abstract

Brazil plays a crucial role in global food security, standing out as one of the world's leaders in agricultural production and the use of biocontrol agents. The fungus Hirsutella thompsonii is widely used in the biological control of mites due to the production of the protein Hirsutellin A, which has acaricidal properties. In this context, optimizing culture media for fungal proliferation is essential for its effective use as a crop biocontrol agent. This study initially aimed to evaluate the efficiency of different submerged culture media (synthetic medium (SM), diluted soybean molasses-based medium (DSM), soybean molasses supplemented with minerals (SMS), and soybean molasses supplemented with minerals and rice bran extract (SMA)) in fungal biomass production, conidia production, metabolites with antioxidant potential, and substrate consumption. Solid-state fermentations using a cooked ricebased medium (supplemented or not with rice bran extract) were subsequently conducted to assess conidia production. The results of the submerged fermentations showed that the synthetic medium (SM) was the most efficient for mycelial biomass production (14.90 ± 0.063 g/L), substrate consumption (92.08 ± 0.69%), and the production of antioxidant compounds (ABTS: 287.86 ± 22.1 mmol TE/g, DPPH: 306.04 ± 0.23 μmol ET. G of extract-1, and Total Phenolics: 826.83 ± 80.37 mg GAE/100 g). Among the soybean molasses-based media, the SMA medium promoted greater mycelial growth (4.42 ± 0.01 g/L), which was not directly reflected in the Total Phenolics values (473.89 ± 36.2 mg GAE/100 g). No conidia production was observed in submerged fermentations, regardless of the medium used. Conidia production was only possible in solid media. However, liquid cultures can be used as a strategy for inoculum expansion for subsequent conidia production in solid media.