The effects of natural substrates and artificial media on the production of conidiospores and blastospores of the entomopathogenic fungus Isaria fumosorosea, strain CCM 8367


Abstract: Entomopathogenic fungus Isaria fumosorosea WIZE (Hypocreales: Cordycipitaceae) is among the most common species used in biological control. The aim of this study was to find the most suitable media for both surface and submerged productions of spores of the strain CCM 8367 of I. fumosorosea isolated in the Czech Republic from the horse chestnut leaf miner, Cameraria ohridella (Lepidoptera: Gracillariidae). For the surface cultivation we used the following commercial agar media: Sabourad dextrose agar (SDA), V8 juice agar (V8J), Corn meal agar (CMA), Czapek dox agar (CDA), Agar malt extract (MEA) and Potato dextrose agar (PDA) and also natural substrates (hulled barley, rice and oatmeal) were tested. For submerged cultivation three standard liquid media were used: Sabourad dextrose broth (SDB), Czapek dox broth (CDB) and Potato dextrose broth (PDB) and two modified media (A and B). The radial growth of the strain and the production of conidiospores was evaluated after 7, 14, and 21 days. Production of blastospores was evaluated daily for 7 days. Best growth of the strain CCM 8367 was observed when two agar nutrient media CDA and SDA were used, while the highest production of spores was observed on medium V8J when fungus produced after 21 days of cultivation 6.28 × 105 conidiospores per mm2 of culture. Production of conidiospores on natural substrates was highest on rice. After 21 days, the production of coniodiospores was 2.58 × 109 per 1 gram of rice. Blastospores production of the strain CCM 8367 was the highest in the modified medium of our own recipe (medium A). After 4 days of cultivation, amount of blastospores per 1 ml in this medium was 3.34 × 108. The best medium producing the highest amount of blastospores among the commercially available artificial media was SDB. The effect of C:N ratio (glucose:peptone) on agarized and liquid media is currently evaluated.

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